US senators vote to end military support in Yemen

US Defence Secretary Jim Mattis speaks to reporters outside the Pentagon on November 28. AP

The US Senate took a defiant stance against President Donald Trump's White House on Wednesday, advancing a measure that would end American military support in Yemen.

Senators voted 63-37 in favour of the proposal just hours after Secretary of State Mike Pompeo and Defence Secretary Jim Mattis had implored them not to curtail US assistance to the Saudi military, arguing that pulling back would worsen the war.

Further debate and votes on the measure are expected next week. But extended debate could serve as a powerful symbolic step - and allow lawmakers to address alternative paths in US-Saudi relations.

Peace talks aimed at ending the war in Yemen have been set for early December in Sweden, between Houthi rebels and the UN-recognised government.

Mattis and Pompeo worry a move to cut US support to the Saudis ahead of the summit is poorly timed and could embolden Houthis not to negotiate.

Senator Murphy, however, said Pompeo and Mattis' testimony may have been counterproductive.

"They lost votes this morning," he said.

US military support for the coalition includes intelligence sharing and training pilots to avoid strikes that risk civilian casualties.

Events have left administration officials publicly grappling with global realpolitik, saying Saudi Arabia's role in countering Iran is too important for the US to turn its back.

The Pentagon chief added that Saudi Arabia is a "necessary strategic partner" and pointed to the US military's training of partner pilots as key in reducing deaths.

"While tragedies occur in war, we assess restraint and improved tactical judgment by Arab coalition pilots has reduced the risk of civilian casualties," he said.

Pompeo warned lawmakers that ending US backing would lead to a stronger Iran, while reinvigorating both the Daesh group and Al Qaeda in the Arabian Peninsula.

"Try defending that outcome back home," he said.