(CNN)As early as the next few days, the Senate will have its best opportunity so far to end US support for Saudi Arabia's devastating war in Yemen -- a war that has sparked a humanitarian catastrophe that puts millions of lives at risk.

The vehicle for congressional action is a bipartisan bill introduced last week by Sen. Bernie Sanders, I-Vermont, Sen. Mike Lee, R-Utah, and Sen. Chris Murphy, D-Connecticut. The bill would end US refueling and targeting assistance for Saudi Arabia's bombing, aimed at Houthi rebels in Yemen, unless such actions are authorized by Congress.

US support for the Saudis -- which includes refueling of Saudi combat aircraft and assistance in choosing bombing targets -- is an act of war as defined by section 8 (c) of the War Powers Resolution. That 1973 law requires congressional approval of any such action, as a way to curb the President's ability to launch a war unilaterally.

Action to end US support for Saudi Arabia's shameful military campaign in Yemen is long overdue. The Saudi regime has used US-supplied aircraft, bombs and missiles to carry out attacks, resulting in thousands of unnecessary deaths when civilian targets such as hospitals, marketplaces, residential neighborhoods and even a funeral were hit.

Even worse, a blockade of Yemen imposed by the Saudi-led coalition has put millions of people at risk of what could become the worst famine the world has seen in decades. In addition, intensive bombing of civilian infrastructure, including water and sewer systems, has resulted in the worst cholera outbreak in living memory.

In the meantime, in an act of astonishing hypocrisy, the Trump administration's UN Ambassador, Nikki Haley, took to the pages of the New York Times earlier this month to imply that the real humanitarian challenge in Yemen has been the firing of a handful of missiles at Saudi Arabia by the Houthi rebel movement, missiles allegedly supplied by Iran.

But Haley's assertions don't stand up to scrutiny. The arms supplied to Saudi Arabia by the United States are far more extensive and have done far more damage than anything Iran may or may not have supplied to the Houthis. During the Obama administration alone, the United States offered to sell Saudi Arabia $115 billion in weaponry, including billions of dollars' worth of bombs and aircraft that are the backbone of that nation's bombing campaign in Yemen.

And contrary to claims by the Trump administration and the Saudi government, the Houthis are a fiercely independent indigenous movement with longstanding political and economic grievances. As Thomas Juneau, an expert on the region who has authored a book on Iranian foreign policy, has noted, the Houthis have their own power base and their own interests in Yemen, and are not a pure proxy for Iran. If anything, uncritical US backing for the Saudi war effort has driven the Houthis closer to Iran than they would otherwise be.

Make no mistake, the Houthis' hands are far from clean. However, enabling Saudi Arabia to bomb and blockade Yemen will do nothing to stop Houthi human rights abuses. Only an end to the conflict can do that.

In addition to sparking a humanitarian crisis of the highest order, the Saudi-led, US-backed war on the Houthis and their allies has opened space for Al Qaeda in the Arabian Peninsula (AQAP) to expand its operations in Yemen. As the International Crisis Group has noted, AQAP has only grown stronger as the Saudi intervention in Yemen has moved forward, and the best way to weaken their grip on the country is to end the civil war. The Houthis had been fighting AQAP prior to the Saudi invasion, and would likely do so again were the war to end.

The Sanders/Lee/Murphy initiative in the Senate is just the latest effort by Congress to rein in US support for Saudi Arabia's brutal war in Yemen. Last spring, the Senate mustered an unprecedented 47 votes against a proposed sale of precision-guided bombs to Saudi Arabia.

And the House, led by Representatives Ro Khanna, D-California, Mark Pocan, D-Wisconsin, Thomas Massie, R-Kentucky, and Walter Jones, R-North Carolina, pressed for an end to US support to the Saudi war effort last year, until their initiative was sidetracked by the House leadership. In an effort to change the subject and shift blame for the consequences of the Saudi intervention in Yemen, the Trump administration and the Saudi regime cited a Saudi decision to temporarily and partially ease its blockade of the port of Hodeida. But the significant elements of the blockade remain in place or have been re-imposed, extending the suffering of the Yemeni people in the process.

To make matters worse, the Saudis have tried to excuse the bombing of civilians in a market in 2016 -- in what Rep. Ted Lieu, D-California, has said "look like war crimes" -- by offering a humanitarian aid package to Yemen that aid groups, like the Norwegian Refugee Council, have noted is insufficient to undo the damage done by the Saudi-led bombing and blockade of the country. A real humanitarian gesture would involve stopping the bombing, fully lifting the blockade and supporting peace talks, without preconditions, that involve all parties impacted by the conflict.

The Senate can improve the prospects for an end to the slaughter in Yemen by supporting the Sanders/Lee/Murphy amendment. The time to act is now, before more people die unnecessarily in a war that has already gone on far too long.