I mean the US offered india to purchase F35 jets even though it is non NATO country
What is logic behind in it ?
Ah I see now. Well the logic is very simple. The US likes to push as further as she can.
IIRC India was asked to drop a prerequisite system for the S-400 from the Russians that in turn meant they couldn't buy the S-400 either. In return for that they were given access to buy the F-35.
Turkey is pushed hard so that she doesn't stray further from US approved weapons and weapon systems. Like I said - NATO doesn't matter when your most important player in the area starts to look at other teams too. They feel the need to push Turkey as much as possible so that she stays firmly inside the US sphere of influence hence the whole story.
The US has used the media to "suggest" sanctions might happen if the S-400 was even considered. Nothing came of that. Then they "suggested" huge embargoes if the deal was inked. That also happened and nothing came of that either. I mean, yes, they did veto "gun sales" (as in literally hand guns) to Turkey to save face but lol
During this whole ordeal the US threatened to "not sell the F-35" to Turkey but that obviously is a big claim to make and even harder matter to actual pull off. This incident is just a continuation of that - they're trying to make the threat look even more credible by voting for it in the senate (which it has absolutely no chance of passing).
The same US declined to sell AntiAir systems to Turkey repeatedly - until the S-400 deal was inked. After that they offered (not accepted a plea - they OFFERED) the patriot systems with tech transfer included! That's still being talked upon I think but not sure.
To summarize : The US uses all her assets to push bully and subdue every and any country except her. To think that Turkey would be spared because she's in the NATO is laughable as the US has done similar things to even the UK.
On the other hand this move is not to stop Turkey from acquiring the S-400 system - that's already happened. This is to make sure Turkey understands that the US means business and a further deal of any kind that that they don't approve of will have some sort of consequences.