Democrats and anti-war activists are sounding alarm bells that the Donald Trump administration intends to enact rarely used emergency powers to transfer precision-guided munitions to Saudi Arabia in an end-run around Congress.

The looming battle over arms transfer comes after the House attached legislation ending US support for the Saudi-led coalition in Yemen to a must-pass defense spending bill on Tuesday. Trump vetoed a similar stand-alone bill last month.

The very next day, Sen. Chris Murphy, D-Conn., an original co-sponsor of the Yemen war powers resolution, blew the whistle on the unusual arms sales maneuver. Congress has blocked the sale of bombs to Saudi Arabia since last year because of concerns for Yemeni civilians.

“I am hearing that Trump may use an obscure loophole in the Arms Control Act and notice a major new sale of bombs to Saudi Arabia (the ones they drop in Yemen) in a way that will prevent Congress from objecting,” Murphy tweeted. He went on to assert that “there is no new emergency reason to sell bombs to Saudi Arabia to drop in Yemen” and that “Trump knows he would lose a vote on the sale in Congress.”