What are the chances of Nuclear attack on U.S being successful?

[Jaxi]

Actually the engineering is pretty easy for a basic nuke, its mostly about obtaining the explosive material. A terrorist wouldn't need a ballistic carrying missile with a Teller-Ulam nuke to do major damage.

No it's not. The "easiest" atomic weapon from an engineering standpoint is a gun-barrel, but that requires a very high purity U-235, which is about .7% naturally abundant. That means you need to isolate it from the much more naturally occurring U-238. U-238 and U-235 cannot be isolated chemically, only by their mass via gaseous diffusion, electromagnetic effects, and thermal diffusion, but all these produce very small yields. Not as simple as a laboratory grade centrifuge. An implosion based atomic weapon is that fucking difficult to build. Look, you have to hold the fissionable material together at a high enough density that would normally scatter it during a criticality event so the neutrons can build. That is a ungodly amount of force you're holding together, and it is only achieved for a few nanoseconds. Even then, the majority of material is scattered, not fissioned. The engineering behind it was so daunting that it was originally dismissed by Oppenheimer and his fellow scientists when they were considering designs for an atomic weapon. It's difficult. Plus, all of this requires a massive investment of infrastructure, money, and time. So no, the engineering is not easy. A dedicated nation can do it, but a terrorist cell operating in America absolutely cannot.

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but some cobbled together dirty bomb that would render an entire city unlivable for decades.

No it won't. It would be extremely expensive and require a massive investment of time and money, but we could decon a city if we needed to. The biggest concern is not the radiation, but internal alpha contamination. That's where the majority of dose would be received.

[ringpriest]

No it's not. The "easiest" atomic weapon from an engineering standpoint is a gun-barrel, but that requires a very high purity U-235, which is about .7% naturally abundant. That means you need to isolate it from the much more naturally occurring U-238. U-238 and U-235 cannot be isolated chemically, only by their mass via gaseous diffusion, electromagnetic effects, and thermal diffusion, but all these produce very small yields. Not as simple as a laboratory grade centrifuge. An implosion based atomic weapon is that fucking difficult to build. Look, you have to hold the fissionable material together at a high enough density that would normally scatter it during a criticality event so the neutrons can build. That is a ungodly amount of force you're holding together, and it is only achieved for a few nanoseconds. Even then, the majority of material is scattered, not fissioned. The engineering behind it was so daunting that it was originally dismissed by Oppenheimer and his fellow scientists when they were considering designs for an atomic weapon. It's difficult. Plus, all of this requires a massive investment of infrastructure, money, and time. So no, the engineering is not easy. A dedicated nation can do it, but a terrorist cell operating in America absolutely cannot.

You're right about the difficult of getting sufficiently enriched fissile material, but wrong about how difficult it would be to make such a bomb.

See the "Nth Country Experiment":

The Nth Country Experiment was an experiment conducted by Lawrence Livermore National Laboratory starting in May 1964 which sought to assess the risk of nuclear proliferation. The experiment consisted in paying three recent young physicists who had just received their PhDs, though had no prior weapons experience, to develop a working nuclear weapon design using only unclassified information, and with basic computational and technical support. "The goal of the participants should be to design an explosive with a militarily significant yield", the report on the experiment read, "A working context for the experiment might be that the participants have been asked to design a nuclear explosive which, if built in small numbers, would give a small nation a significant effect on their foreign relations."

The experiment ended on April 10, 1967, after only three man-years of work over two and a half calendar years. According to a heavily redacted declassified version of the summary, it was apparently judged by lab weapons experts that the team had come up with a credible design for the technically more challenging implosion style nuclear weapon. It is likely that they would have been able to design a simpler gun combination weapon even more quickly, though in such a case the limiting factor in developing such a weapon is not usually design difficulty but rather the procurement of material (enriched uranium).

[Sledfang]

No it's not. The "easiest" atomic weapon from an engineering standpoint is a gun-barrel, but that requires a very high purity U-235, which is about .7% naturally abundant. That means you need to isolate it from the much more naturally occurring U-238. U-238 and U-235 cannot be isolated chemically, only by their mass via gaseous diffusion, electromagnetic effects, and thermal diffusion, but all these produce very small yields. Not as simple as a laboratory grade centrifuge. An implosion based atomic weapon is that fucking difficult to build. Look, you have to hold the fissionable material together at a high enough density that would normally scatter it during a criticality event so the neutrons can build. That is a ungodly amount of force you're holding together, and it is only achieved for a few nanoseconds. Even then, the majority of material is scattered, not fissioned. The engineering behind it was so daunting that it was originally dismissed by Oppenheimer and his fellow scientists when they were considering designs for an atomic weapon. It's difficult. Plus, all of this requires a massive investment of infrastructure, money, and time. So no, the engineering is not easy. A dedicated nation can do it, but a terrorist cell operating in America absolutely cannot.

No it won't. It would be extremely expensive and require a massive investment of time and money, but we could decon a city if we needed to. The biggest concern is not the radiation, but internal alpha contamination. That's where the majority of dose would be received.

I agree that the engineering was daunting, but now there aren't that many secrets anymore and the know-how is out there. Also I think your combining engineering too directly with the macro-challenge of investment, logistics, infrastructure, separation, and time. Building a nuke isn't as much hard as it is difficult to get the international political acceptance to do it openly. Also the post you replied to assumed that it would be constructed in the US, which has never been thought of as the most realistic path. I think it is well known that a terrorist cell wouldn't be doing most of the engineering themselves, but instead they would be sneaking a near finished product along with the resources to sustain an operation from an existing foreign country. Of particular concern is Pakistan, which has deep security issues.

[Annoying]

Actualy,
A, Russia has enough firepower to obliterate the US, China does too (to a degree, but mostly No)
B, They are bad, they announced the first ever intercept of a technologically inferior missile a year ago or so, its a worthless boondoggle, and there are joint cheifs saying that on record.
C, only Russia and, as i said to a degree, the Chinese have sufficient range on the missiles, the nominal range of some NK ones have a chance off hitting something (France and Britain has sufficient range too).
Israel, Pakistan, and India, the remaining nuclear powers do not have missiles capable of hitting the US.
India and Israel (the latter is allegedly) have Nuclear submarines, and thus range is Moot (as well as defences), (France, Britain, and China does too, but as they have sufficient range, its moot)

Uh, the area of the US is 3.79 million square miles. (9.83 million km^2).

"367 ICBMs with 1,248 warheads" according to the RSNF. 367x(pi*r^2) = 9.83 million km^2.

A bit of algebra: pi*r^2 = 9.83 million/367 ---> r^2 = 26784.7/pi --> r = sqrt(8525.86) ---> r = 92.3km. That means every ICBM would have to have an effective radius larger than that of the destructive radius of the largest bomb ever dropped, which had a radius of ~85km in terms of 3rd degree burns. The largest Russian ICBM carries 10 warheads @ 150kt each, which puts them at 0.2% of the yield of that bomb.

When I said "entirely", I meant entirely. Which is why it wouldn't happen.

The reason I limit it to ICBMs is because they aren't as easy to intercept. They enter space and orbit, and drop 1-n reentry vehicles. We already have systems to catch non-space-based missiles at almost a 100% rate.

[Deleted]

People really underestimate the technology that the US possesses.
No missile attack from a country can ever hit the United States. Isreal's Iron Dome is ancient technology from the 90's when cell phones weren't even in color yet and extremely effective still, so imagine what the US has under it's sleeve.

You seem to have no idea what an ICBM is and how it works, it's only a 'missile' (rocket actually) to get to the sub-orbital trajectory, after it goes through all it's stages the warheads are released and use gravity to get where they need to go. What the Iron dome does is childsplay compared to shooting down multiple warheads that are coming down , they have no heat signature since they are not rocket propelled at that point, they are pretty small so hard to lock with radar, they go with terminal speeds of +5000 m/s (+18.000 km/h !!) at reentry which means minutes to hit once they reenter, many Russian (and the US ofc too) ICBM's also have something called penetration aid (ie chaffs, decoys, jammers , hell some MIRV buses even have stealth capabilities ), ie the SS-18 Satan (Russia still has 59 in operation i think atm) with it's 10 warheads is equipped with 40 heavy decoys which appear as warheads to any defensive system, making each single missile as hard to intercept as 50 single warheads, so that makes 2950 'warheads' to shoot down if they all get launched and that is just the ss-18's (which they could technically also fully outfit with real warheads btw but current treaties prevent ICBM's carrying more as 10 warheads) ^^ gl shooting them all down, not gonna happen. Those things are damn hard to shoot down because that is exactly what they were designed for. Most tests trying to shoot down dummy warheads from ballistic missiles by the US had a pretty high failure rate so a pretty high % will hit their designated targets if not all.
Which is the reason the US is trying to build the ABM system in Europe so ICBM's can be 'caught' during the ‘mid-course’ phase, and why Russia is so heavily opposed to this system.

[Ecwfrk]

Am I right to assume that there is less than 1% chance of it ever happening?

If someone has nukes and wanted to use them against the US, they'd probably be successful. I can't imagine it'd be much harder for someone with those kinds of resources to get something inside our border than it is for a guy with a 1952 pickup to smuggle in a few hundred pounds of cocaine.

They wouldn't be as successful as our retribution would be though. Which is probably why it hasn't happened. Not only are we working to keep it from happening, so is the rest of the world. Because what we might do in response is terrifying. Look what happened when a glorified street gang blew up a few buildings and planes in the US. If someone used a nuke on the U.S., we'd probably end up the only country in existence and turn our attentions on potential terrorist threats from Venus.

There's well over a dozen countries with nuclear capability.

Last I heard, it was 38. Only 9 (as far as we know) actually have nuclear weapons under their control though. The rest use their nuclear capabilities only for non-weapons purposes, most often voluntarily.

[apepi]

I think it is more likely the US would bomb itself.

[Realtalk]

You don't want any country with nukes to get hit period. They will respond in kind and all human life on earth will die. Studies show as little as 20 going off at any one time will be enough to destroy us all.
Read up on Israel's Sampson option. Which states if the country is ever truly in danger of falling they will launch all their nukes in every direction Britain, Russia, Iran, Africa etc..thus ensuring if they go down they take the world with them.

[Budong]

You don't want any country with nukes to get hit period. They will respond in kind and all human life on earth will die. Studies show as little as 20 going off at any one time will be enough to destroy us all.
Read up on Israel's Sampson option. Which states if the country is ever truly in danger of falling they will launch all their nukes in every direction Britain, Russia, Iran, Africa etc..thus ensuring if they go down they take the world with them.

And this is exactly why the U.S. continually supports and will always support Israel. They are probably the most likely country to ever use nukes in warfare and we understand that we can never let that happen.

Now why we ever let them have nukes in the first place is another debate. Fact is they have them and will use them if they feel overwhelmed. It's better to simply support them to the point that they never feel like they have to.

[Ecwfrk]

You don't want any country with nukes to get hit period. They will respond in kind and all human life on earth will die. Studies show as little as 20 going off at any one time will be enough to destroy us all.

Those models are all based so much shaky presumptions they're laughable. The purpose of such "studies" is only to promote disarmament. They always conclude with something like the most recent one did in their abstract "Knowledge of the impacts of 100 small nuclear weapons should motivate the elimination of the more than 17,000 nuclear weapons that exist today".
It's just data to support a conclusion, that's not science.

For example, these studies assume and require that every nuke dropped create a massive firestorm. Without a monstrous firestorm the climate effects of a nuclear explosion are relatively negligible. Firestorms aren't easy to create.

based on World War II experience with mass fires resulting from air raids on Germany and Japan, the minimum requirements for a firestorm to develop are considered by some authorities to be the following: (1) at least 8 pounds of combustibles per square foot of fire area (40 kg per square meter), (2) at least half of the structures in the area on fire simultaneously, (3) a wind of less than 8 miles per hour at the time, and (4) a minimum burning area of about half a square mile.

The chances of those conditions being met in any city large enough to be a target for destruction these days are minimal thanks to most having very tall buildings built with fire resistant materials that make excellent baffles and would prevent a large enough amount of material from igniting in a small enough area to create a firestorm from a single detonation no matter how large it was.

The risk of global extinction from nuclear weapons use is almost negligible as you'd have to specifically target cities susceptible to firestorm and hit them when conditions are right to meet the doomsday scenarios in the computer models.

Read up on Israel's Sampson option. Which states if the country is ever truly in danger of falling they will launch all their nukes in every direction Britain, Russia, Iran, Africa etc..thus ensuring if they go down they take the world with them.

Makes for good rhetoric doesn't it? If it were actually true though, you can bet there'd be measures in place by at least Russia and the US to ensure it could never, ever actually happen.

[tiporispit]

So the hypotheticals are: 100%, nukes already launched, heading toward the US, what are the chances it...

A) Destroys us entirely?
B) All or most of them hit?
C) A single one hits?

That's a lot of options.

A is outright gone. No one has enough nukes to do that, and all the largest of them aren't ICBMs and could never make it here.
B is interesting. Obviously the actual stats of our ICBM intercepting systems are classified. There's no way it's 100%, but I'd like to hope it's up there.
C is nearly a guarantee with enough launched at us. No countermeasure is 100%, and even with good ones, there's no way to catch a large swath of them coming from all sides.

Not quite. The Patriot missiles were an abysmal failure in the first Gulf War. While they claimed something like 90% efficiency, post-war documents showed less than 10%, and that was against ancient, conventional, single-payload Russia missiles. A few thermonuclear air detonations would wipe out the guidance systems, even IF the modern interceptor missiles were actually effective. When you combine the fact Russia has ICBMs and SLBMs with MIRV technology, and 3,000 warheads with the fact that little old Mesa, AZ is the 50th largest city in the United States, it quickly becomes apparent that nothing worthwhile would remain of America, which is why MAD has worked for over 60 years.

[Herecius]

Well, all it really takes is somebody willing and able to pull the trigger, so the chances of an attack being *successful*? Probably not really all that bad.

The chances of the retaliation being the equivalent of getting fucksmashed into the stone aged? 127%.

[Shiny212]

The US doesn't have rocket shields, if someone nukes the US, said area will be destroyed.

[rogueMatthias]

Nukes are SO last century. Its all about biological warfare now!

[Rindrae]

the only way i can see it is if its a dirty bomb or something smuggled in. not a direct air strike or anything though, the US defense grid is incredibly tight.

[Athabaska]

If you mean missles, then probably not. If you mean some sneaky terrorist attack, then who knows.

[Slant]

Is this about likelihood or success chances? Likelihood is still near 0% if MAD holds up and Putin doesn't go bonkers totally. Success chances are 100% at all times if Russia freaks out. Unless you can shoot down several thousand missiles and their dozen or so warheads each within 30 minutes.

[Grummgug]

Here is the most likely scenario.

Given a nation that currently has nuclear weapons and is stable politically. Over the course of 30 years, they destabilize politically and then an extremist group takes control of the country. Then they go crazy and launch their nukes at the US.

For a specific example, France has about 300 nuclear missiles. Let's say they suddenly begin to destabilize politically, and then the government is overthrown and a radical group takes control of the nation, seizes the missiles, and launches them at the US. That's really the only way it happens in modern times.