A top U.S. general warned on Tuesday that Islamic State would pose an enduring threat following a planned USA withdrawal from Syria, saying the militant group retained leaders, fighters, facilitators and resources that will fuel a menacing insurgency.
"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 Armed Services Committee hearing.
"I was not consulted", he added.
He said between 1,000 to 1,500 IS fighters remain in that area, though noted thousands more had "gone to ground" elsewhere in Syria.
Iranian President Hassan Rouhani said Tuesday that President Donald Trump's expressed wish to keep US forces in Iraq in order to monitor neighboring Iran has exposed American "lies" about fighting terrorism.
Sen. Angus King, I-Maine, asked: "So you weren't consulted before that decision was announced?". "Certainly we are aware that he has expressed a desire and an intent in the past to depart Syria".
National Security Adviser John Bolton has since stated that the US will only withdraw once ISIS is defeated and the safety of allied Kurdish fighters is secured, although Trump said plans remain unchanged.
Despite Trump's order to withdraw, American officials maintain that the goal remains the "enduring defeat" of the Islamic State group and are moving ahead with a long-planned meeting of top diplomats from the 79-member US-led anti-Islamic State coalition this week.
The article warns that the "precipitous withdrawal of United States forces" from either country "could put at risk hard-won gains and United States national security".
During an interview with CBS television aired on Sunday, Trump reportedly said that the important role of USA troops in Iraq is "to watch Iran", sparking anger and rejection in Iraq.
Trump is expected to discuss foreign policy in the address to a joint session of Congress, including declaring the Islamic State militant group all but defeated.
It is unclear whether Trump's triumphant tone will echo the warnings coming from different parts of his administration, including Votel's Central Command and the U.S. military.
According to the report, U.S. Central Command believes that ISIS fighters will continue to conduct "opportunistic attacks" on U.S. troops as they withdraw.
It said the group was interested in attacking aviation and using chemical, biological, radiological and nuclear materials and that there were up to 18,000 Islamic State militants in Iraq and Syria, including up to 3,000 foreign fighters.
At nearly the same time the report was released, the US Senate was approving an amendment critical of Mr Trump's Syrian and Afghanistan withdrawal.