Congressional critics of US involvement in the war in Yemen are up in arms following a recent report in The New York Times revealing that the Donald Trump administration has stationed a dozen US Army Green Berets on the Saudi border as part of the fight against Iran-backed Houthi rebels.

The Trump administration maintains that US support for the Saudi-led coalition is limited to targeting, logistics, intelligence and midair refueling support for coalition warplanes. But in recent months the US role in the war has fallen under heightened scrutiny from lawmakers as coalition bombings result in mounting civilian casualties and the country struggles with famine and the worst cholera outbreak in history.

“The Trump administration’s purposeful blurring of lines between train-and-equip missions and combat, from Niger to Yemen, is unacceptable,” Sen. Tim Kaine, D-Va., told Al-Monitor in a statement. “It runs afoul of our system of checks and balances in war powers and is deepening our involvement in endless wars without a vote of Congress.”

Progressive champion Sen. Bernie Sanders, I-Vt., and Tea Party stalwart Sen. Mike Lee, R-Utah, forced a floor vote on ending US participation in the war after House leadership forestalled a similar effort by Rep. Ro Khanna, D-Calif., last year in the lower chamber. Although the Senate blocked the joint resolution 55-44, the vote reflected growing bipartisan frustration with the war — frustration that continues to fester.