WASHINGTON (Reuters) - The general overseeing U.S. forces in the Middle East said on Thursday that he was under no pressure to withdraw forces from Syria by any specific date, after President Donald Trump ordered the drawdown of most U.S. troops from Syria.

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“What is driving the withdrawal of course is our mission, which is the defeat of ISIS, and so that is our principal focus, and that is making sure that we protect our forces, that we don’t withdraw in a manner that increases the risk to our forces,” U.S. Army General Joseph Votel, head of the U.S. Central Command, said during a House Armed Services Committee hearing.

“There is not pressure on me to meet a specific date at this particular time,” Votel said.

Trump ordered the withdrawal of all 2,000 U.S. troops in Syria in December after he said they had defeated Islamic State militants in Syria. The abrupt decision sparked an outcry from allies and U.S. lawmakers and was a factor in Jim Mattis’ resignation as defense secretary.

But Trump was persuaded by advisers that about 200 U.S. troops would join what is expected to be a total commitment of about 800 to 1,500 troops from European allies to set up and observe a safe zone being negotiated for northeastern Syria.

About 200 other U.S. troops will remain at the U.S. military outpost of Tanf, near the border with Iraq and Jordan.

Some lawmakers were critical of Trump’s announcement to draw down troops from Syria and were concerned about the impact on allies.

“In terms of the public perception, the international perception is that prior to that Tweet it wasn’t planned, he sent it out and now we are responding,” Democratic Representative Adam Smith, the chairman of the House Armed Services Committee, said.

In December, Trump put a video on Twitter where he said U.S. troops were leaving Syria.

Votel said Russia viewed Trump’s announcement positively.

“It puts Russia more in the driver’s seat ... It solidifies their presence in the Middle East,” Votel said.

Thousands of people could still be left inside Islamic State’s last enclave in eastern Syria, the U.S.-backed Syrian Democratic Forces (SDF) said, as waves of evacuations from the tiny area continued on Thursday.

The SDF has said it wants to ensure all civilians have been evacuated before launching a final assault on the besieged enclave of Baghouz. It is the last shred of populated territory held by Islamic State, which once controlled swathes of Iraq and Syria.

Votel said he believed that Islamic State militants being evacuated from the remaining territory controlled by the militant group were largely “unrepentant, unbroken and radicalized.” He said the militant group was waiting “for the right time to resurge.”

“We will need to maintain a vigilant offensive against this now widely dispersed and disaggregated organization that includes leaders, fighters, facilitators, resources and toxic ideology,” Votel added.

A U.S. official, speaking on the condition of anonymity, said acting Pentagon chief Patrick Shanahan spoke with his French counterpart and other European allies on Syria. He is expected to speak with other European allies next week.