US President Donald Trump’s May 8 decision to directly arm the Syrian Kurdish People’s Protection Units (YPG) against the Islamic State did not surprise anyone. If anything, the United States stated what it had been doing for some time.

Since the United States began conducting airstrikes against IS in August 2014 and the US Congress passed legislation to train and equip Syrian Kurds in December 2014, the YPG and YPG-led Syrian Democratic Forces (SDF) have fought against IS with great success. Thanks to US support, the SDF has reversed the territorial gains of the extremist Sunni group and, since spring 2016, has been marching toward IS’ capital, Raqqa.

Indeed, as Al-Monitor’s Fehim Tastekin noted in May 2016, the US partnership with Syrian Kurds to liberate Raqqa from IS has been going on for quite some time. But this situation has long angered America’s erstwhile ally, Turkey. Ankara possesses the second-largest military in NATO and considers the YPG an offshoot of the Kurdistan Workers Party (PKK), which both Ankara and Washington consider a terrorist organization.

Interestingly, so far, the Turkish response to the Trump administration’s decision has been tough but reasonable, at least considering that Turkish President Recep Tayyip Erdogan had lashed out against the United States and its Western partners for “supporting terrorists in Syria” in December 2016.