WASHINGTON — Amid reports President Trump is considering more American military help for the Saudi-led fight in Yemen, U.S. lawmakers are urging caution, if not an about-face.

Four U.S. senators have offered legislation to limit arms sales to Riyadh over its troubled Yemen campaign. Fifty-five members of the U.S. House called on Trump in a letter to end both U.S. refueling for Saudi coalition warplanes and logistical assistance for the Saudi-led bombings in Yemen — and they said Trump must seek congressional approve before he deepens U.S. military involvement.

The push-back comes amid several reports that Trump is considering assistance for an offensive on a key port held by rebels in Yemen, and that he is allowing arms sales that stalled under President Obama to Saudi Arabia and its coalition partner Bahrain. Late last month, America's top commander for the Mideast, told Congress said "there are vital U.S. interests at stake" in the Yemen fight. 

According to the United Nations, more than 7,600 people have been killed in the two-year-old civil war between Houthi rebels and the internationally-recognized government of Yemeni President Abdrabbuh Mansour Hadi. The Saudi-led coalition of nine African and Mideast nations, which backs Hadi, has been criticized for alleged strikes on civilian targets.

On Wednesday, the U.N. high commissioner warned that Yemen is on the brink of famine and called for the coalition to end its two-year naval blockade. Amid reports Trump is mulling support for a coalition offensive on the port al-Hudaydah, 38 nongovernmental organizations last week called on him to reconsider, arguing the operation would deny food and medicine to the suffering civilian population.

The U.S. military has provided support to the Saudi-led air campaign since 2015, including a U.S. advisory mission in the Saudi operations headquarters and aerial refueling for Saudi jets, but the Obama administration sought to scale back that support last year.

Since the start of fiscal 2017, the Defense Security Cooperation Agency has seen the State Department clear two major weapons requests for Saudi Arabia: a request for aerostat surveillance systems, worth an estimated $525 million, and a request for CH-47F Chinook helicopters, estimated at $3.51 billion. The helicopter sale is important to the U.S. Army because it brings down the per-cost for the helicopter and keeps the Chinook line warm during an upcoming production gap.

Senators who opposed Obama's intervention in Yemen announced legislation Thursday to require Trump certify Riyadh is targeting terrorist groups, minimizing harm to civilians and facilitating humanitarian assistance before Congress can consider the sale or transfer of air-to-ground munitions to Saudi Arabia.

U.S. Sens Chris Murphy, D-Conn., Rand Paul, R-Ky., Al Franken, D-Minn., and Dick Durbin, D-Ill., announced the legislation, citing the many civilian casualties of the Yemen civil war, "and a security vacuum that has empowered our terrorist enemies," al-Qaida and the Islamic State group.

"Saudi Arabia is an important ally in the region, but it's important that our relationship be on the right terms. Their troubling record of human rights abuses, their war in Yemen, and their exportation of extremism deserve close scrutiny if our partnership is to continue," Durbin, the Senate's No. 2 Democrat, said in a statement.

Under the Arms Export Control Act, U.S. sales or transfers of arms to foreign governments must be proposed by the State Department and then approved by Congress. If Congress approves the sale, the administration is then permitted to finalize and implement the transfer. 

The Murphy-Paul legislation, like a bill they introduced last year, would add a step to the approval process by requiring the president to attest that Saudi Arabia is concretely demonstrating its anti-terror efforts and protection of civilians before Congress can consider the sale. The bill offered last year did not advance out of the Senate Foreign Relations Committee.

The 55 U.S. lawmakers who called on Trump to seek congressional approval before involving the U.S. in a major war. They said they were troubled by reports that al-Qaida in Yemen had emerged as a de facto ally in the war against Iran-backed Houthi rebels — as Saudi coalition forces had reportedly fought alongside them in several battles, and coordinated with Saudi-financed Islamist militias.

Reps. Mark Pocan, D-Wis., and Justin Amash, R-Mich., Ted Lieu, D-Calif., and Walter Jones, R-N.C. organized the letter, whose other signatories were all Democrats. 

"Such an attack could push the country into full-blown famine, where nearly half a million children in Yemen are facing starvation," Pocan said in a statement accompanying the letter. "Congress is a direct line to the people and this letter is a first step in reasserting our Constitutional check on presidential powers. I am committed to pursuing all tools at our disposal to ensure President Trump abides by our Constitution before possibly plunging our country into another senseless conflict."

Aaron Mehta in Washington contributed to this report.

Email:    jgould@defensenews.com                           

Twitter:    @reporterjoe

Joe Gould was the senior Pentagon reporter for Defense News, covering the intersection of national security policy, politics and the defense industry. He had previously served as Congress reporter.

More In Congress