"We say, 'No, we are not very good at that.' "It's not our responsibility".
Another air strike of the coalition's warplanes on a civilian facility raises a question "how long will the coalition help terrorists to bomb and destroy Syria?".
Brett McGurk, the Department of State's senior envoy to the anti-Islamic State coalition, told the Washington Post that President Trump's policies are directly responsible for the significant gains made by the anti-ISIS coalition in the last 6 months.
Such areas include Mosul, where US-backed Iraq security forces declared victory over ISIS last month.
Dillon said so far more than 80 percent of ISIS attacks against SDF forces have been carried out by hidden explosives.
"The attacks that happened in Paris and Brussels، the attackers were trained by them and left from Syria to Europe،" he said.
"We estimate that there are about 2,000 ISIS fighters left in Raqqa", he added.More news: White Sox OF Garcia concussed after colliding with teammate - Article
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The recapture of Raqqa would mark a major milestone in the three-year effort to defeat Daesh.
Key changes under President Trump that have brought about the ISIS changes.
The United Nations has estimated that 25,000 civilians also remain there.
The two leaders also spoke about "countering Iranian malign influence", according to a readout of the call provided by the White House.
President Donald Trump said on Thursday the US-Russian relationship was at "an all-time and very unsafe low", and Russia said new sanctions imposed by Washington meant an end to hopes for better ties with the Trump administration.
Officials had earlier said that about 3,000 people in the country were known by them for posing a threat and who were under investigation, but there are 20,000 others who have featured in previous inquiries and are categorized as posing a "residual risk", the Times quoted Whitehall sources as saying in May.
There was no obvious specific target for the strikes, though the U.S. has been generally targeting ISIS forces within the city to try to back the Kurdish-led invasion.