(New York Times) -- The Trump administration has long applied a double standard to the violence in Yemen, the world’s worst humanitarian crisis. It fiercely condemns Iran for supporting the indigenous Houthi fighters and allegedly supplying them with short-range ballistic missiles and other weapons. At the same time, it has nothing bad to say about (and is indeed enabling) Saudi Arabia’s savage bombing in support of Yemen’s government — an air campaign that is worsening a civilian death toll among a population already suffering from a famine and cholera.

That Iran is providing the Houthis with missiles and other weapons has not been proved.

For the moment, however, Saudi Arabia’s bombing campaign and its blockade of Yemen’s major ports and airports are the main drivers of the crisis. The United States has provided the Saudi-led coalition, which includes the United Arab Emirates and other Persian Gulf states, with precision-guided munitions, intelligence and refueling capability.

At a recent press conference at a military base near Washington, Nikki Haley, the United States ambassador to the United Nations, conspicuously ignored America’s involvement. Among the props displayed were pieces of what Pentagon officials claimed were Iranian-made Qiam missiles, including one allegedly fired by Houthi militants at an airport in the Saudi capital, Riyadh, last month.

Not a word was said about Saudi-American cooperation in the war, and officials, in response to basic questions from reporters, were unable to prove their charges about the source of the missiles. The purpose of this dog-and-pony show — the Pentagon declassified the weaponry for the occasion — was to reinforce the administration’s campaign to rally international support for punishing (and perhaps, someday going to war against) Iran on grounds that Tehran is largely responsible for destabilizing activities in the region.

The whole performance was eerily reminiscent of Colin Powell’s presentation to the Security Council as secretary of state in 2003 (which he later came to regret) of the case for war against Iraq, in which he accused Iraq of hiding weapons of mass destruction.

Iran, though sympathetic to the Houthis, provided limited support for the war effort until 2015, when Saudi Arabia, determined to do whatever was necessary to check Tehran’s influence, began the first of more than 15,000 airstrikes, killing thousands of civilians and turning the Yemen fighting into a proxy war. With Yemen dependent on imports for most basic needs, Saudi Arabia tightened the siege further last month by imposing a land, sea and air blockade after a missile allegedly fired by the Houthis came close to Riyadh.

Despite all this, the Saudi-led coalition has failed to defeat the Houthis, who now control the capital, Sana. Meanwhile, the toll on Yemen, the poorest country in the Middle East, is mounting: Some 10,000 people have died, eight million are at risk from famine and nearly one million have contracted cholera.

President Trump, eager for close ties with the new Saudi leadership, has largely turned a blind eye to the humanitarian crisis. The administration has been under mounting pressure from members of the Senate who have threatened to cut aid to Saudi Arabia and who delayed until Dec. 19 the confirmation of Mr. Trump’s pick for State Department legal adviser, Jennifer Newstead. It also is being pushed by international aid and human rights groups to persuade Riyadh to stop the carnage.

There are other pressures as well. Ms. Newstead told the Senate Foreign Relations Committee that Saudi Arabia could be violating American and international law by restricting the flow of humanitarian aid to Yemen. Human rights advocates have called for imposing United Nations sanctions on Mohammed bin Salman, the Saudi crown prince, and other coalition officials directing the Yemen war.

There are signs the administration is beginning to listen and even exert a constructive influence on the Saudis, who last week said they would open the main port of Hudaydah for 30 days so humanitarian aid can flow. Even so, a long-term solution to the war will take far more than that.

For starters, the Saudis could fully lift the blockade and challenge the Houthis and the Iranians to join in an immediate unconditional cease-fire. This is just the sort of opening Mr. Trump could be urging; if he has the kind of relationship with the Saudis that he boasts about, he might get them to listen — and save countless Yemini lives in the bargain.