The only reason it got close is because the Destroyer, which keep in mind is primarily an air-defense warship, decided not to blow it out of the sky the second the SU-24 got in range of the Destroyer's ordinance. That hardly qualifies as a "troll". It's like those time Russia sends it's Tu-95s to just outside the Alaskan border, the US Air Force rolls its eyes, send F-22s to intercept them, and escort them further out to sea.
That's defining down "combat worthy" to something barely meaningful. Under your definition, a peer like the F-111 Aardvark would still be combat worthy. Hint: it isn't... it's been out of the US Air Force for nearly 20 years, and Australia is ridding / has gotten rid of it's last reserve Aardvarks.
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That's comparing apples and oranges. The A-10 is good for one thing and one thing alone. If we were to say make a "New A-10" like single-mission aircraft, it would look identical to the A-10 in almost every respect, probably with more titanium, a different gun and more modern avionics. But it would be essentially the same, because the A-10 is what a heavily armed CAS aircraft looks like. This is one of the reasons the A-10 survives. The design is proven and affordable. Hell the navy is doing this too in a sense: it's not building anymore DDG-1000 Zumwalt class destroyers after the first 3. It's going to build dozens of Flight-IIA and Flight III Arleigh Burke class destroyers (a 1980s design) because of the intrinsic strength of the basic design. Another example is the M1 series tank. The Army is preparing bidding on the M1A3, which is expected to be 20 tons lighter than the M1A2 and replace most of the M1A1 fleet. It will look very much like the M1A2 externally, but internally, it's going to be somewhat different. The design though, simply works.
The Su-24 is a different case. It is comparable to the F-111 Aardvark. Now don't get me wrong, the F-111 Aardvark was a very good aircraft and performed the "medium bomber" role pretty well. The SU-24 was a nominal peer. I say nominal because he Su-24 was a shittier version of it even then. It had a much smaller range and could carry less ordinance. It's electronics were less sophisticated. It has seen some upgrades, but here is the rub: it's an aircraft meant for a penetrating role, but due to lack of stealth and modern ECM cannot perform that role. This is why the F-111 Aardvark was phased out in the late 1980s (then entirely in the 1990s) as the F-117 and B-1Bs came onto the scene, and starting taking missions the F-111 did just a few years earlier (like Operation El Dorado Canyon).
So no. It's not combat capable, except if you mean "it can fly with weapons, and launch them if it doesn't get shot down first". Against AEGIS Warships, designed to destroy SU-24s mind you, it is useless. Against modern American fighters it can't out run or out manuever, it is useless.
The fact it is flying is a testament to the decrepit nature of the Russian aircraft industry, capable of making glorified stunt show aircraft - one or two at a time mind you - and not comprehensive, modernized combat systems.
The T-72 is from the generation prior to the M1. It is a 1970s era tank. The M1 Abrams is a 1980s era. Furthermore the T-72 has seen very few upgrades (and what Upgrades there are not widely deployed). Russia instead relies upon it's immense numbers of tanks. The M1 on the other hand has seen constant upgrades that have been widely distributed. First generation M1s have been entirely mothballed. The US Army relies mostly on the 6000 M1A1s and M1A2s built in the 1990s and 2000s. The older M1A1s will be retired over the next decade as the lighter (but still conceptual, to be fair) M1A3 is purchased.
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The JSF can't do anything yet. Because it isn't done. You're basically damning an unfinished program for being unfinished. Because it's a fighter program that will be producing fighters through 2045 and is only in low rate initial production of ~20 units a year out of an eventual expected production run of 3500. By 2017, that will be around 112 per year, then up from there. I'm terribly sorry our next generation fighter isn't done being next generation yet.
And when it is? When it is done? When 3500 it is in the hands of countries that are US Military allies but not Russian military allies? What then? Russia isn't even remotely close to anything comparable in terms of the technology it brings to the table. Sure... I'm sure Sukhoi can turn out another SU-27 variant that impresses at stunt shows. But the airframe isn't what makes the F-35 advanced. It's the computers, the sensors and the electro-optical targeting system. It's this especially - the notch under the nose:
Mocking the F-35 for it's troubled history is ultimately a losing argument. No one in this forum has skewered Lockheed Martin worse than me for the entire program when given the opportunity. That company represents everything wrong with government contracting. Everything. However that is mostly an argument about taxpayers getting fleeced by a corporation very intent on milking the biggest military contract in human history for every cent. It is not an argument about what is actually being produced and what will be produced. The DoD is going to pay whatever it takes to make the F-35 what it wants it to be. So at the end of the day, the promised aircraft - albeit at an exorbitant price - is exactly what we'll get... a successor to the F-16 and F-117, in absolutely immense numbers.
But that's the future. The future is fun, but it's not here yet. Most rich NATO countries being armed with the most advanced stealth attack aircraft in the world, ten years hence, is very much tomorrow's problem (not that Russia will have an answer to it, besides pretending that an evolved S-300/S-400/S-500/S-600 system somehow offers defense against long range anti-radiation missiles). At the present Russia faces active aircraft, from F-15s to F-22s, far more capable than anything it has. So snarkiness about the F-35 is pretty pointless, because it wouldn't be what kills Russians. Advanced systems that are actively deployed, would be doing that.
Not that NATO is going to be killing Russians anytime soon. Well at least directly.