WASHINGTON ― U.S. lawmakers on Thursday left Pentagon briefings on the Syria crisis frustrated with the tangle of problems that came with President Donald Trump’s decision to pull troops from Syria and voicing new fears the Islamic State will regroup to wage terror.

Defense Secretary Mark Esper and Joint Chiefs Chairman Gen. Mark Milley met with the Senate and House armed services committees Thursday and offered assurances the counter-Islamic State fight remained a top priority. But they were pressed to explain how the fight could be effectively prosecuted after the U.S. withdrawal alienated its critical ally, the Syrian Kurds.

Lawmakers refused to discuss the contents of the two classified meetings, but voiced their worries afterwards, including about how the U.S. would protect Kurds from NATO ally Turkey’s invasion of northern Syria and protect American troops in the crossfire ― and whether reports of Islamic State militants escaping Kurdish-run prisons means that new terror attacks are on the horizon.

Emerging from HASC’s Syria briefing, Readiness Subcommittee Chairman John Garamendi, D-Calif., said: “I do know that ISIS will be back and that the black flags will be back” ― a reference to the banners that once marked swaths of Syria and Iraq controlled by ISIS.

The fighting between Turkish and Kurdish forces has sparked Western concerns that the Syrian Democratic Forces, holding large swathes of northern Syria once controlled by Islamic State, would be unable to keep thousands of jihadists in jail and tens of thousands of their family members in camps, Reuters reported this week.

The region’s Kurdish-led administration told Reuters that 785 Islamic State-affiliated foreigners escaped the camp at Ain Issa but the British-based war monitor Syrian Observatory for Human Rights, citing sources in the camp, said around 100 people had escaped.

“Turkey and the Kurds must not let them escape. Europe should have taken them back,” Trump wrote on Twitter. “They will never come to, or be allowed in, the United States!”

To crush the Islamic States regional caliphate, the U.S. had provided Syrian Kurds with training and air support, and under Trump, weapons. Without them, HASC Chairman Adam Smith, D-Wash., said his main question was, “Who are our partners going forward in our effort to contain the ISIS threat in Syria and Iraq?” (Smith otherwise expressed confidence in the safety of U.S. troops as Milley and Esper’s top priority and confidence in the safety of American nuclear weapons at Incirlik Air Base in Turkey.)

Beyond the hearing rooms, bipartisan support was emerging Thursday for the U.S. to maintain its own assets in the region, in part to ensure that the Islamic State does not gain ground. At the same time lawmakers were also focused on sanctions legislation aimed at deterring Turkey from slaughtering Kurdish forces and civilians, and several proposals were introduced publicly on Thursday.

In light of a potential ISIS threat to the region and the U.S., "We have to continue to have a presence in areas of Syria that ISIS is populating,” SASC ranking member Jack Reed, D-R.I., told reporters. “We have to be able to maintain overflight, we have to be able to strike, and it’s more complicated now because I don’t think we can assume we have the same access or overhead coverage that we had.”

“I assume our human intelligence network was pretty well decimated now that we’ve given up the best sources of information with our relationship with the Kurds. I don’t know what the Iraqis will do in allowing us to operate from the region ― so we are in the process now of, on the run, trying to come up with another strategy to deter and continue to defeat ISIS,” Reed said.

SASC Emerging Threats and Capabilities Subcommittee Chair Sen. Joni Ernst, R-Iowa, on Thursday offered legislation to give the Pentagon and State Department 30 days to provide a strategy to prevent ISIS from growing. In a floor speech, she recalled ISIS once “controlled territory larger than the United Kingdom" and that it both inspired and directed attacks in the U.S.

“In our fast-moving and quickly-changing world, it is easy for some to forget the terrible threat ISIS once posed while they were at their most powerful, but it would be wrong to think we could now allow ourselves to take our foot off of our enemies’ throat,” Ernst said.

Earlier in the day, Senate Majority Leader Mitch McConnell, R-Ky., and a vocal critic of Trump's decision to pull U.S. troops from Syria, said he wanted to pass a resolution condemning the move that would be “even stronger” than the one that passed the House on Wednesday with broad bipartisan support.

McConnell criticized Democrats for not including in a recent resolution anything about the need to keep troops in Syria over the long term. “It is backward-looking. And it is curiously silent on the issue of whether to actually sustain a U.S. military presence in Syria, perhaps to spare Democrats from having to go on the record on this key question," McConnell said in a floor speech.

Sens. Lindsey Graham, R-S.C., and Chris Van Hollen, D-Md., announced their Turkey sanctions proposal Thursday. If enacted, it would remain until the administration certifies Turkey has halted attacks against the Syrian Kurdish communities, has withdrawn from all locations that they didn’t occupy prior to the Oct. 9 invasion, and is not hindering counterterrorism operations against ISIS. (SASC members Richard Blumenthal, D-Conn.; Jeanne Shaheen, D-N.H., and Marsha Blackburn, R-Tenn., were among the co-sponsors.)

“Erdogan’s invasion of northeastern Syria has created the conditions for the reemergence of ISIS and the destruction of our allies. These outcomes must not only be addressed by the administration but by Congress as well,” Graham, the Senate’s lead appropriator for the State Department, said in a statement.

Thursday also saw Turkey sanctions proposals from House Foreign Affairs Committee Chairman Eliot Engel, D-N.Y., and ranking member Michael McCaul, R-Texas., as well as Sens. Jim Risch, R-Idaho, and Bob Menendez, D-N.J., who are the chairman and ranking member of the Senate Foreign Relations Committee, respectively.

Risch, in a floor speech outlining the complicated situation, defended Trump from criticism he caused the current crisis, which Risch called “simply a political statement that isn’t true.” “This was a war that has been going on between these two groups for centuries. It was going to happen," Risch said of the Turkish incursion.

The action came the same day the U.S. and Turkey agreed to a five-day cease-fire in the Turks’ attacks on Kurdish fighters in northern Syria, meant to allow the Kurds to withdraw to roughly 20 miles away from the Turkish border.

The agreement essentially gives the Turks what they had sought to achieve with their military operation in the first place. After the Kurdish forces are cleared from the safe zone, Turkey has committed to a permanent cease-fire but is under no obligation to withdraw its troops. In addition, the deal gives Turkey relief from sanctions the administration had imposed and threatened to impose since the invasion began, meaning there will be no penalty for the operation.

The White House released a letter on Wednesday in which Trump warned Erdogan that the sanctions could destroy his economy and that the world “will look upon you forever as the devil if good things don’t happen. Don’t be a tough guy. Don’t be a fool!”

Democrats emerging from the meetings with defense officials said they worried even the best laid strategy could be upended by a comment or tweet from Trump. Smith expressed confidence in Esper and Milley, but said the president’s habit of erratic remarks, “creates problems with friend and foe alike in having a consistent, coherent strategy.”

“So I am worried about how the president’s various statements impact any effort to build a decent strategy,” Smith said. “One minute he’s saying we’re going to sanction Turkey back into the Stone Age to force a cease fire, the next he’s saying we don’t care about the Kurds anyway. Those are not helpful messages to what those gentlemen are trying to do, policy wise.”

In a similar vein, but stronger, Reed excoriated Trump’s “acquiescence” to the Turkish incursion and said it was clear Trump hadn’t heeded the advice of Esper, Miller or any of his national security experts. The pullout had upended the administration’s stated goals of defeating ISIS, removing Iranian-aligned forces and fostering a U.N. brokered settlement to Syria’s civil war.

“The security and humanitarian catastrophe that President Erdogan has unleashed with Trump’s approval will make achieving any of these goals nearly impossible,” Reed said.

The Associated Press contributed to this report.

Joe Gould was the senior Pentagon reporter for Defense News, covering the intersection of national security policy, politics and the defense industry. He had previously served as Congress reporter.

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