Micah Zenko has been covering the war on Yemen and the U.S. role in it since the beginning. He marks  the second anniversary of the start of the war by reviewing its costs and commenting on its futility:
Other than dropping weapons with an unconscionable lack of discrimination and proportionality, it appears there are no clear goals and objectives to this day.
On a personal note, in the nearly 20 years of having had the privilege of working and interacting with U.S. national security officials and staffers, I have never followed an issue that virtually nobody can justify or defend [bold mine-DL]. Military officers who have watched or played a role in the Saudi-led bombing campaign are especially sickened by the brutality and strategic pointlessness of the airstrikes.
The war on Yemen and our government’s support for it have been indefensible from the start, and on the few occasions when U.S. officials have been pressed to explain why the U.S. is involved they have had to resort to echoing Saudi propaganda or simply making things up to deflect attention from what is being done to Yemen and its people. The reason virtually no one can justify or defend the policy is that there is no good reason for what our government is doing there, nor is there any good reason for what the coalition is doing. The standard explanation for our role is that Obama wanted to “reassure” the clients in the Gulf of Washington’s backing, but that has always been an unconvincing and frankly pathetic excuse for enabling war crimes and helping to create the world’s worst humanitarian disaster.
The frustrating reality is that both the Obama and Trump administrations have been able to back the war without ever having to face much serious scrutiny from Congress or most of the media, and so they have not had to defend a policy that has shamefully encountered relatively little criticism and minimal resistance. Even when the U.S. role in fueling and arming the coalition’s planes has been acknowledged in reports, it is often mentioned only in passing and then minimized as much as possible. It is very difficult to organize opposition to a policy that most people in the country may not even know is happening. I suppose it is good that our officers are sickened by what the U.S. has been helping the Saudis and their allies do, but most of our politicians and policymakers don’t appear to be bothered in the least. On the contrary, the administration is considering how to deepen our involvement and make things even worse.