With the Islamic State (IS) on the run across Syria, the Donald Trump administration has committed to using US Armed Forces in the country to counter Iranian influence.

Its refusal to publicly provide details — or a legal justification — for its military strategy, however, is raising bipartisan concerns in Congress that the United States could be drawn further into conflict with a wide array of actors in Syria’s complex civil war with no timeline for withdrawal.

Testifying before the Senate Foreign Relations Committee on Thursday, David Satterfield, the acting assistant secretary of state for Near Eastern affairs, outlined US goals in Syria as finishing off IS, stabilizing northeastern Syria and countering Iranian influence. But he declined to publicly disclose what activities US forces in Syria are engaged in outside of the counter-IS campaign, raising bipartisan alarm bells.

“That won’t pass muster,” committee Chairman Bob Corker, R-Tenn., interjected. “I’m sorry. You can generally state what the purpose of our military is beyond [IS] without getting into any kind of classified materials.”