President Donald Trump has ordered the Department of Defense to deploy additional combat-equipped U.S. forces to the Middle East, dramatically escalating America’s posture in the region amid intensifying attacks by Iranian-backed Houthi militants.

In a formal letter dated March 28 and released Tuesday, Trump notified House Speaker Mike Johnson and Senate President Pro Tempore Chuck Grassley of the move, citing persistent threats to American troops and commercial vessels in the Red Sea. The new troop surge comes as U.S. forces carry out their fourth consecutive week of airstrikes on Houthi-controlled areas in Yemen.

“I will no longer allow this band of pirates to threaten and attack United States forces and commercial vessels in one of the most important shipping lanes in the world,” Trump wrote. “We will act to keep Americans safe.”

The president said the military campaign would continue until the Houthis no longer pose a threat to navigation or to U.S. personnel operating in the region.

Trump’s directive is grounded in his authority as commander in chief and consistent with the War Powers Resolution, which requires presidents to report significant military activity to Congress. While the deployment is ongoing, Trump has made clear that the goal is deterrence, not prolonged engagement.

“The choice for the Houthis is clear,” Trump posted on Truth Social earlier this month. “Stop shooting at U.S. ships, and we will stop shooting at you.”

The Houthis, a designated terrorist organization, have repeatedly targeted American and allied naval assets since the October 2023 Hamas terror attacks on Israel. At least three U.S. Reaper drones have been downed since March 3. The Houthis have so far avoided engaging ships from China and Saudi Arabia, prompting questions about the group’s coordination and geopolitical motives.

In addition to military action, the Trump administration has stepped up economic pressure on the Houthis. Last week, the Treasury Department sanctioned the International Bank of Yemen (IBY), accusing it of enabling the militants to sidestep international sanctions and fund terror activities through global payment systems like SWIFT.

“Financial institutions like IBY are critical to the Houthis’ ability to fund attacks,” Deputy Treasury Secretary Michael Faulkender said, adding that the administration had frozen assets linked to IBY chairman Kamal Hussain Al Jebry and two top executives.

Defense analysts note that while the Houthis remain a serious regional threat, they have been significantly degraded in recent weeks. Trump has publicly claimed that “many” Houthi commanders were killed in U.S. strikes and that the group has been “decimated.”

Still, the potential for escalation remains. Iran—widely acknowledged as the Houthis’ primary sponsor—has yet to respond directly, but Pentagon officials are monitoring for signs that Tehran could retaliate, either through its proxies or through more direct means.

Tuesday’s letter is expected to spark debate in Congress, but Republicans are likely to back Trump’s hardline stance. With the administration making clear this is a national security red line, lawmakers are now on notice: the U.S. is not backing down.

As one White House official put it, “This isn’t a message just for the Houthis. It’s a message for anyone thinking of testing us.”