A top U.S. general warned on Tuesday that Islamic State would pose an enduring threat following a planned U.S. withdrawal from Syria, saying the militant group retained leaders, fighters, facilitators and resources that will fuel a menacing insurgency.

The remarks by U.S. Gen. Joseph Votel, head of the U.S. military's Central Command, represent the latest warning by current and former U.S. officials about the risk of a resurgence by Islamic State following a planned U.S. withdrawal from Syria ordered in December by President Donald Trump.

"We do have to keep pressure on this network. ... They have the ability of coming back together if we don't," Votel told a Senate hearing.