Trump did something that on the surface looks stupid, hideous, and is being used to stir up problems with even his most loyal supporters.
But it's far more complicated.
Turkey is and has had it's problems, but has tried to stay a democratic nation and is a member of NATO. While the country is predominately Muslim, they have for the most part tried to stay a secular state. That is until recently when there has been a push from radicals to become more "Islamic".
If you studied biblical history you know that what is modern day Turkey is home to some of the earliest Christian settlements. Jews had spread from Israel up along the Mediterranean coast into modern day Greece (all part of the Roman Empire at the time).
Syria is another mixed bag of nuts. Various ethnic groups and religions. The majority is Sunni Muslim. Pardon my spelling, but the country is ruled by the Baath party. They believe in an Arab Renaissances, socialism and one party rule. They are predominately Shia Muslim.
The Kurds are a part of the non-Arab Sunni group. They have been sniping at Turkey for decades as well as Iraq and Syria. They are aligned with nobody but themselves, and just to be clear, not all Kurds agree even on the time of day. They want a homeland, their own country, which they intend to carve out of the countries that surround them, Turkey, Syria, Iraq and Iran (minor). The US first started to arm the Kurds when they were fighting Saddam. All well and good until they took those weapons and turned them on a NATO Ally, Turkey. The Kurds had no time for Saddam and no time for ISIS, they don't want to be subjugated by anyone. Therefore the US was their friend in the sense that the enemy of my enemy is my friend.
The Syrian war refugees and the terrorist attacks from the Kurds have put a serious strain on Turkey. Turkey is a NATO ally and has long been a base of operations to spy on the former Soviet Union and Iran. I can tell you from work with NATO in the 80's and 90's that the Turks did not want to visit air defense radar sites in the border region with Syria and Iraq for fear of being grabbed by Kurdish fighters. The feeling was if you got pulled over and had an American passport you were safe - safer, than if you were Turkish.
It's a shithole, always has been a shithole, and will probably continue to be a shithole until they kill every last one of themselves, it;s tribal / ethnic and religious warfare, they all claim the same land, they all want the same thing, which is the land and the other guy gone.
That's just as simple a summary as I could come up with. 10,000 years of history in 1000 characters