With how Trump coward in front of Putin and how he refuses to have Americans in the room when they talk, I am thinking he has something BIG on Trump. Basically Putin has Trump by the balls by the looks of it.
And while normally I would think that is enough to keep Trump in line given by Trumps actions thus far, between the fact that Trumps mind continues to turn to mush and the fact Trump will be in his last term without much to lose, I he MIGHT be willing to defy him this time.
That is unless Putin has someone or multiple people close to Trump that can deal with Trump when ordered and Trump knows about it and can't do anything about them. Or he has something so big that not even the presidency could save him from the fallout.
So really hard to say right now if Trump is willing to defy the guy who he into a bitch on national TV for.