A Saudi-led coalition has been carrying out a military campaign in neighboring Yemen since March 2015, after large swaths of the country fell under the control of the Houthis — a religious-political extremist group hostile to the Saudis.
The Gulf kingdom, together with Egypt, Morocco, Jordan and other Middle Eastern and North African countries, initially launched a series of airstrikes on the Houthi-held areas, as well as imposing an air and naval blockade of the country.
From the beginning, the US provided the coalition with intelligence, airborne fuel tankers and bombs. It is thought that apart from supporting its longtime ally Saudi Arabia, the Obama administration's move was a bargaining chip aimed at appeasing the Saudis over the US-Iran nuclear deal.
However, over the last couple of months the situation has escalated, with the involvement of Saudi Arabia's ground troops and private military companies, whilst a bolstered Al-Qaeda has been filling the power vacuum.
The prolonged airstrikes have also killed and wounded thousands of innocent Yemeni civilians, sparking global outrage from human rights groups.
Some in the US have become critical of the decision by the White House to support Saudi Arabia's military adventurism.
"As I read the conflict in Yemen, I have a hard time figuring out what the US national security interests are," Democratic Senator Christopher S. Murphy, said during a congressional hearing weeks ago.
The administration's response has been that, while the US is keen on helping the Saudis in its fight against the Houthis, it does not mean it will aid and abet it in all its proxy wars with Iran throughout the Middle East.
The head of the Middle Eastern policy in the White House, remarkably pointed out that even if the US supported the Saudi-led campaign in Yemen:
"This is not our [the US'] war."
Wednesday, in a letter to the New York Times, Human Rights Watch's legal and policy director James Ross contested Obama's administration.
"American support for the Saudi-led coalition […] makes the United States a party to the conflict in Yemen under international law. This obligates Washington to investigate coalition airstrikes that may be war crimes for which American forces may be liable," Ross wrote.
"Given the coalition's repeated unlawful attacks in Yemen over the last year, which Human Rights Watch and others have documented, the United States should cease selling bombs to Saudi Arabia or risk complicity in civilian deaths," he added.
The West's stance towards the conflict in Yemen has been controversial. While the EU has condemned the strikes last month, and passed a non-binding vote in favor of a Saudi arms embargo, the UK has kept supplying them with weapons.