Turkey will take over the fight against Islamic State militants in Syria as the United States withdraws its troops, President Tayyip Erdogan said on Friday, in the latest upheaval wrought by Washington's abrupt policy shift. The surprise announcement by U.S. President Donald Trump this week that he would withdraw roughly 2,000 troops has felled a pillar of American policy in the Middle East. Critics say Trump's decision will make it harder to find a diplomatic solution to Syria's seven-year-old conflict. For Turkey, the step removes a source of friction with the United States. Erdogan has long castigated his NATO ally over its support for Syrian Kurdish YPG fighters against Islamic State. Turkey considers the YPG a terrorist group and an offshoot of the armed Kurdistan Workers' Party (PKK), fighting for Kurdish autonomy across the border on Turkish soil. In a speech in Istanbul, Erdogan said Turkey would mobilize to fight remaining Islamic State forces in Syria and temporarily delay plans to attack Kurdish fighters in the northeast of Syria – shifts both precipitated by the American decision to withdraw. The news was less welcome for other U.S. allies. Both France and Germany warned that the U.S. change of course risked damaging the campaign against Islamic State, the jihadists who seized big swathes of Iraq and Syria in 2014-15 but have now been beaten back to a sliver of Syrian territory. Likewise, the U.S.-backed militia spearheaded by the YPG said a Turkish attack would force it to divert fighters from the battle against Islamic State to protect its territory. A U.S. official, speaking on condition of anonymity, said American troops may continue to operate against Islamic State in Syria. The Pentagon is considering using Special Operation teams based in Iraq to target militants in Syria, the official said. The official emphasized that using special operators on the ground was one of many options being considered, was still in the planning stages and that no final decision had been made.