Opening a 79-nation conference in Washington on the fight against the group also known as ISIS, Pompeo also called on other nations to do more -- including by funding Syria and Iraq and agreeing to bring home extremists jailed by Syrian Kurdish allies.

"America will continue to lead in giving those who would destroy us no quarter," Pompeo said.

"We ask each of your countries to stand with us and, through our efforts and God's help, the day will come when the permanent defeat of ISIS is a reality," Pompeo said.

He described Trump's controversial order in December to withdraw all 2,000 US troops to Syria as "essentially a tactical change" and not a shift in commitments.