"He pulled them out of Syria." and into Iraq (still in ME)
"While the US has withdrawn from Syria"
no it hasn't... 'around 300 soldiers would remain in the U.S. military's Al Tanf base in the south, the officials said.'
https://www.nbcnews.com/news/world/trump-orders-u-s-forces-withdraw-further-syria-esper-says-n1065516
"Iran is at the heart of the current crisis in Iraq. The US have concentrated on dealing with IS there."
I take it you mean in Iraq, not in Iran. Iraq, where the US forces have been in force since 2003.
"Just two weeks after President Donald Trump triumphantly declared the “100 percent” defeat of ISIS’s caliphate,"
https://www.politico.com/magazine/story/2019/03/18/trump-isis-terrorists-defeated-foreign-policy-225816
Infinite supply of enemies, home grown and imported.