The short story (read below to understand it all, here is the incomplete but critical story):
After an attempted coup in Turkey, which their President blames at least in part on the United States, Turkey arrested over one hundred thousand possible conspirators. An American Pastor was swept up in these arrests. The Pastor and his family appear to be innocent - but we haven't cooperated in picking up a Turkish Religious figure in the United States that President Erdogan has loaded the blame upon. So Turkey is holding our Pastor, hoping to exchange him for an America based Turkish citizen he blames for the coup.
Side-bar, the Turkish citizen in America does not seem to be the instigator of the coup. However, if (I said IF) America had an interest in the new outcome or, worst, was tipped off the coup was coming, the Turkish guy here might be who we would have informed about it. IF any of that was true, we don't want to hand over an innocent man.
The Americans want the US Pastor released and the administration has worked hard to make it happen. The latest effort included a complex series of moves in which we provided some relief and Israel was going to release a Turkish woman. Everything seemed to happen, except that hte Pastor wasn't released.
The administration was furious and President Trump was furious, since his base is loudly saying the Pastor knew nothing. And Trump isn't furious quietly.
Erdogan said he wouldn't cave to America and there was no deal for the Pastor. Now he, like Trump, has painted himself into a corner with his political base.
Trump has loudly more than doubled the tariffs on Turkish Steel and Aluminum. This has pushed the already weak Turkish Lira lower and made it more wobbly. It is also illegal and should have been done quietly another way. (It is illegal because we said the tariffs were a security issue and therefore had to be consistent across nations - we are in of breach on the WTO which we set up.)
It matters because Turkey is an ally with a lot of information and an US Air Base and Russia is waiting to welcome them (and our info) into their waiting arms.
It's going to get ugly