Human rights advocates and Yemeni activists are voicing their frustration after a US Senate resolution to end the United States' involvement in the destructive and deadly war in Yemen was rejected.

The Senate voted 55-44 on Tuesday against the motion, which called for an end to US military aid to Saudi-led coalition forces fighting in Yemen that had not been directly approved by Congress.

Shireen al-Adeimi, a doctoral student at Harvard University who is originally from Yemen, said she was "extremely disappointed" by the fact the resolution was killed before it could be brought up for discussion on the Senate floor

"At this point, three years later and so many human lives later, it feels like such a criminal act that they won't even acknowledge this," Adeimi told Al Jazeera in a telephone interview.

The Saudi-led intervention in Yemen, with U.S. support, has been a humanitarian disaster. Instead of supplying bombs and refuelling capabilities, we should be doing everything possible to create a peaceful resolution to that civil war and provide humanitarian help. — Bernie Sanders (@SenSanders) March 20, 2018

A bipartisan group of US Senators - Bernie Sanders of Vermont, an independent, Republican Mike Lee of Utah and Democrat Chris Murphy of Connecticut - introduced the resolution at the end of February.

Later, co-sponsored by a total of 14 senators, the motion sought to invoke the War Powers Act, a law that seeks to restrict the US president's ability to go to war without congressional approval.

If passed, it would have required President Donald Trump to withdraw US troops from hostilities in Yemen within 30 days.

The motion stated the US has provided Saudi-led forces with "aerial targeting assistance, intelligence sharing, and mid-flight aerial refuelling", and assistance in aerial targeting and the coordination of military and intelligence activities.

"What we are saying is, if Congress wants to go to war in Yemen or any place else, vote to go to war. That is your constitutional responsibility," Sanders said on the Senate floor on Tuesday.

He said critics of the motion would argue US troops are "not really engaged" in Yemen.

"Tell that to the people of Yemen whose homes and lives are being destroyed by weapons marked 'Made in the USA', dropped by planes being refuelled by the US military on targets chosen with US assistance," Sanders said.

Humanitarian crisis

Saudi Arabia launched a military offensive in Yemen in 2015. Its stated purpose was to root out Yemen's Houthi rebels, who had taken over the country's capital, Sanaa, and forced out Saudi-backed President Abd-Rabbu Mansour Hadi.

More than 10,000 Yemenis have been killed since the war began, tens of thousands have been wounded, and another two million people have been displaced.

Living under what has been described as the gravest humanitarian crisis in decades, Yemenis face severe food, water and medicine shortages, and a devastating outbreak of cholera, which has affected nearly one million people.

Every house has its own sad story in Yemen now. They don't even have time to stop and think about it… The amount of killing and death is horrible. Radhya al-Mutawakel, chairperson and cofounder of Mwatana Organization For Human Rights

At the end of 2017, United Nations officials said, "Yemen remains on the cusp of one of the largest famines in modern times."

Radhya al-Mutawakel, chairperson and co-founder of Mwatana Organization For Human Rights, an independent Yemeni organisation, said the Senate vote result was "very depressing".

"It was time for something different to be done," Mutawakel told Al Jazeera over the phone from Sanaa on Wednesday.

She said countries such as the US, UK and France have the power to stop the war in Yemen since they provide military and political support to Saudi Arabia and its coalition partners, such as the United Arab Emirates.

"But instead they are fuelling the war by the arms trade and by political support to some members in the Saudi-led coalition," Mutawakel said.

She said life in Yemen is getting worse by the day and that virtually every Yemeni citizen has experienced the loss of a loved one.

"Every house has its own sad story in Yemen now. They don't even have time to stop and think about it… The amount of killing and death is horrible," she said.

"Most Yemenis are civilians. They are victims of the war, but they are not involved. They want peace, they want this war to stop."

War powers

The Senate vote was not the first challenge to the US role in Yemen in the past year.

In November, the US House of Representatives passed a non-binding resolution that called on US forces to end "unauthorised hostilities" in the Saudi-led bombing campaign in Yemen.

An earlier version of that motion sought to directly challenge US involvement in Yemen under the War Powers Act, but it was eventually watered down after opposition from both Democrat and Republican leaders.

Rita Siemion, international legal counsel for US-based advocacy group Human Rights First, said US legislators are "really starting to realise the importance of playing a role in deciding where, when and why the US uses military force".

Under the US Constitution, Congress has the power to decide if the US can go to war, while the president has limited authority to engage in defensive force to respond to an attack, she explained.

In the case of Yemen, the US executive branch has argued its support for Saudi-led forces does not mean it is engaged in hostilities.

"What they've said is, we're doing things like helping refuel their aeroplanes, providing intelligence, targeting assistance, but our forces are not themselves directly engaged in that conflict," Siemion told Al Jazeera.

The US' use of drone and missile attacks against Al-Qaeda in the Arabian Peninsula and other groups in Yemen has largely gone unchallenged, however, and was not included in the Senate resolution this week.

US Senator Bob Corker, who chairs the Foreign Relations Committee, said he expects to present a new Authorisation for Use of Military Force next month, US media recently reported.

The US still relies on war authorisations that were passed in 2001, in response to the 9/11 attacks, and in 2002, to allow for military action in Iraq.

Siemion said any future war authorisation law must include several specific provisions, including clear geographic limits and mission objectives, strong reporting requirements and a commitment to respect international law.

It must also include a time limit on any military action.

"The sunset clause is really kind of the most critical of all of these so that we avoid these never-ending, forever wars that are constantly morphing," she said.

"[It] means that Congress has to come back and decide what continued authorities are still needed, if any, and make those adjustments."

Saudi leader in US

The Yemen motion also came up for a vote on the same day Mohammed bin Salman, the Saudi crown prince, met the US president in Washington.

Bin Salman, known in the West as MBS, began a two-week visit to the US on Monday that aims to solidify the US-Saudi relationship, rehabilitate his country's image and secure investments as part of a plan to diversify the Saudi economy.

Trump and bin Salman "discussed the threat the Houthis pose to the region" in their meeting and additional steps to deal with the humanitarian situation in Yemen, the White House said in a statement on Wednesday morning.

The leaders "agreed that a political resolution to the conflict is ultimately necessary to meet the needs of the Yemeni people", the statement read.

The US and Saudi Arabia have maintained strong ties for decades.

Last year, Trump announced a $110bn weapons deal with the Saudi government from Riyadh, where he chose to go on his first official visit abroad since becoming president.

Adeimi expressed frustration that bin Salman is "going around unchallenged" in the US, despite being "the architect of the worst humanitarian crisis on Earth".

She added, however, it is important for Yemenis to know the unsuccessful Senate vote doesn't mean the fight is over.

"The good news is there were 44 senators who voted to talk about this… which is substantial, given the cover-up, so to speak, and how little attention this has been getting," Adeimi said.

"This isn't the end. We're going to continue. We're going to find ways to continue bringing attention to this conflict and bringing an end to this conflict."