Vermont’s congressional delegation expressed adamancy Friday that President Donald Trump seek approval from Congress to intervene further in Syria. The delegation’s three members appeared less certain of how they would vote if Trump did, in fact, come to them with such a request.

Trump ordered a missile strike on a Syrian air base late Thursday in retaliation for the government’s alleged chemical weapons attack, which killed at least 80 civilians earlier this week. Some members of the U.S. Congress have commended Trump while others have condemned his unilateral decision.

“Only Congress has the power to make war,” U.S. Rep. Peter Welch (D-Vt.) said in an interview Friday morning. “From my perspective, both the president and the Congress are failing to meet their constitutional obligation to get an authorization from Congress before they use military force.”

Neither Sen. Patrick Leahy (D-Vt.) nor Sen. Bernie Sanders (I-Vt.) immediately responded to requests for interviews. But in a written statement issued Friday morning, Sanders said, “As the Constitution requires, the president must come to Congress to authorize any further use of force against the Assad regime.” In his own statement, Leahy said, “The president is now required to give Congress notification under the War Powers Act.”

Both senators stopped short of criticizing Trump for authorizing air strikes Thursday.

Vermont’s delegation expressed greater ambivalence about how Congress should respond to a potential request for authorization from the president.

“It’s a hypothetical, but here’s what I would say: There is a place for the use of force as a deterrent against a barbaric regime that is using chemical weapons,” Welch said. But, he added, “I would not vote for us getting involved militarily in another war in the Middle East.”

Welch said he would have to see a concrete plan from Trump before coming to any definitive conclusion. “It’s extremely concerning to me that the president does not have any plan for what the U.S. is gonna do — not just about the chemical weapons but about Syria and the Middle East in general.”

Sanders gave little indication of how he might vote on future air strikes.

“The Trump administration must explain to the American people exactly what this military escalation in Syria is intended to achieve, and how it fits into the broader goal of a political solution, which is the only way Syria’s devastating civil war ends,” the junior senator said in his statement. “Congress has a responsibility to weigh in on these issues.”

Similarly, Leahy argued that Syrian President Bashar al-Assad “must be held accountable.” But, the senior senator added, “We must keep in mind that we have learned that there are grave risks and unintended consequences in the use of military force, especially unilateral military force. When used it should be in self-defense or part of a larger strategy in conjunction with our international partners, and with the broad support of the American people.”