This is all noise that happens in open democracy, S-400 and any other deal will get waivers and same goes for deals done with US, besides so far TOT hasn't been any issue while dealing with the US. We haven't recived any and under the current deals we just switch out key items such as datalinks, coms, IFFs anyways. People seem to confuse due process & procedure to conclusions. Indian lobby is strong and so is the trade lobby that wants to do business with India. Neither Dems or GOP are mad enough to have massive ongoing contracts or upcoming ones into jeopardy by not granting waivers.
Trump is more than allowed to have his trade wars, they are perfectly important since they have massive trade defecits with everybody and as a leader whose core interest is to his citizens & his re-election, does he really give two shits about anybody's feeling, not really. For years they have had unfair trade practices that have bled US jobs and having tarrifs or even talk of them gets people around the table and that's the whole idea.
Indian leaders could learn somethings from him, focus on own interest people. The EU can suck on it's own burgeing phalus since they're running easily one of the most corrupted institutions in the world, it will crumble under it's own weight folks, it's not a matter of if but a matter of when. As for Trump sticking it to Iran well the Jews are powerful people and the EU should be very careful back stabbing them (a second time). They virtually dominate the global Financial markets, these hebrews can fuck with you without ever firing a shot.
The US isn't getting more desperate, if anything it's getting stronger than ever folks, focusing on itself. From a red hot job market to massive reinvestment back into US, largest ever defence budget, the US is making a strong come back, the GDP numbers are miles better.