The top U.S. general in the Middle East says the fight against ISIS is far from over, Defense One reports.

“We should be clear that what we are seeing now is not the surrender of ISIS as an organization, but a calculated decision to preserve the safety of their families and preservation of their capabilities by taking their chances in camps for internally displaced persons and going to ground and remote areas and waiting for the right time to resurge,” Gen. Joseph Votel told the House Armed Services Committee on Thursday.

“Reduction of the physical caliphate is a monumental military accomplishment, but the fight against ISIS and violent extremism is far from over,” he added.

ISIS once controlled swaths of Iraq and Syria but still heavily populates the besieged enclave of Baghouz in eastern Syria.

The Syrian Observatory for Human Rights on Wednesday said preparations were underway in eastern Syria to announce the end of ISIS there, but Votel warned of a different approach.

“We will see low-level attacks, we’ll see assassinations, we’ll see IED attacks, we’ll see ambush type things as they begin to emerge from this,” he said.

Trump in December announced a troop withdrawal from Syria but backed off following criticism.