During the Yemeni civil war, Saudi Arabia led an Arab coalition of nine nations from the Middle East and parts of Africa in response to calls from the internationally recognized pro-Saudi president of Yemen Abdrabbuh Mansur Hadi for military support after he was ousted by the Houthi movement due to economic and political grievances, and fled to Saudi Arabia.
Nations such as the United Kingdom and the United States support the Saudi Arabian-led intervention in Yemen primarily through arms sales and technical assistance. France had also made recent military sales to Saudi Arabia. MSF emergency coordinator Karline Kleijer called the US, France and the UK part of the Saudi-led coalition, which imposed the weapons embargo and blocked all ships from entering Yemen with supplies. Human rights groups have criticized the countries for supplying arms, and accuse the coalition of using cluster munitions, which are banned in most countries. Oxfam pointed out that Germany, Iran, and Russia have also reportedly sold arms to the conflicting forces. Tariq Riebl, head of programmes in Yemen for Oxfam, said, "it's difficult to argue that a weapon sold to Saudi Arabia would not in some way be used in Yemen," or "if it's not used in Yemen it enables the country to use other weapons in Yemen." Amnesty International urged the US and the UK to stop supplying arms to Saudi Arabia and to the Saudi-led coalition.
It called on the international community, including the United States and United Kingdom to stop "providing arms that could be used in the conflict in Yemen". On August 3, 2019, a United Nations report said the US, UK and France may be complicit in committing war crimes in Yemen by selling weapons and providing support to the Saudi-led coalition which is using the deliberate starvation of civilians as a tactic of warfare.
Arab coalition
Allegations of Iranian involvement The coalition accused Iran of militarily and financially supporting the Houthis. On 9 April US secretary of state John Kerry said there were "obviously supplies that have been coming from Iran", with "a number of flights every single week that have been flying in", and warned Iran to stop its alleged support of the Houthis. Iran denied these claims.
Anti-Houthi fighters defending Aden claimed they captured two officers in the Iranian Quds Force on 11 April, who had purportedly been serving as military advisers to the Houthi militias in the city. This claim was not repeated. Iran denied presence of any Iranian military force.
According to Michael Horton, an expert on Yemeni affairs, the notion that the Houthis are an Iranian proxy is "nonsense".
According to Agence France-Presse, a confidential report presented to the Security Council's Iran sanctions committee in April 2015 claimed that Iran had been shipping weapons to the Houthi rebels since between 2009 and 2013. The panel further noted the absence of reports of any weapon shipments since 2013.
On 2 May, Abdollahian said that Tehran would not let regional powers jeopardize its security interests.
According to American officials, Iran discouraged Houthi rebels from taking over the Yemeni capital in late 2014, casting further doubt on claims that the rebels were fighting a proxy war on behalf of Iran. A spokeswoman for the US National Security Council said that it remained the council's assessment that "Iran does not exert command and control over the Houthis in Yemen."
On 6 May, Iran's supreme leader, Ayatollah Ali Khamenei, said, "The Americans shamelessly support the killing of the Yemeni population, but they accuse Iran of interfering in that country and of sending weapons when Iran only seeks to provide medical and food aid."
On 26 September 2015, Saudi Arabia alleged that an Iranian fishing boat loaded with weapons, including rockets and anti-tank shells, was intercepted and seized in the Arabian Sea, southeast of the Omani Port of Salalah, by Arab coalition forces. In May 2019, Houthi militias launched two attacks to two pumping stations managed by Saudi Aramco. Anas AlHajji, an oil expert, said that such an attack is planned to damage the said pipelines as they replace the Strait of Hormuz's oil passages.
United States
In March 2015, President Barack Obama declared that he had authorized US forces to provide logistical and intelligence support to the Saudis in their military intervention in Yemen authorized by the Yemeni government, establishing a "Joint Planning Cell" with Saudi Arabia. This includes aerial refueling permitting coalition aircraft more loitering time over Yemen, and permitting some coalition members to home base aircraft rather than relocate them to Saudi Arabia.
According to press reporting, many in US SOCOM reportedly favor Houthis, as they have been effective at combating al-Qaeda and recently ISIL, "something that hundreds of US drone strikes and large numbers of advisers to Yemen's military had failed to accomplish". According to a senior CENTCOM commander, "the reason the Saudis didn't inform us of their plans is that they knew we would have told them exactly what we think—that it was a bad idea." As Yemen expert Michael Horton puts it, the US had been "Iran's air force in Iraq", and "al-Qaeda's air force in Yemen". According to an Al Jazeera report, one reason for US support may be the diplomatic logic of tamping down SA's opposition to the Iranian nuclear deal by backing them. Another is the view among some US military commanders that countering Iran took strategic priority over combating Al-Qaeda and ISIL.
On 30 June, an HRW report stated that US-made bombs were being used in attacks indiscriminately targeting civilians and violating the laws of war. The report photographed "the remnants of an MK-83 air-dropped 1,000-pound bomb made in the US".
US Representative Ted Lieu has been publicly raising concerns over US support for Saudi-led war in Yemen. In March 2016, he sent a letter to Secretary of State John Kerry and Secretary of Defense Ash Carter. He wrote in the letter that the "apparent indiscriminate airstrikes on civilian targets in Yemen seem to suggest that either the coalition is grossly negligent in its targeting or is intentionally targeting innocent civilians". Following American concern about civilian casualties in the Saudi-led war in Yemen, the US military involvement is mostly ineffective due to coalition's airstrikes targeting civilians and hospitals.
In 2015, the United States deployed The Green Berets to assist the Saudi Arabian military with missile interception.
A March 2016 Human Rights Watch report states that US participation in specific military operations, such as selecting targets and aerial refueling during Saudi air raids "may make US forces jointly responsible for laws-of-war violations by coalition forces"."Yemen: Embargo Arms to Saudi Arabia" Human Rights Watch, 21 March 2106 In September The Guardian reported that one in three bombing raids hit civilian sites."One in three Saudi air raids on Yemen hit civilian sites, data shows" The Guardian, 16 September 2016.
On 13 October 2016, fired Tomahawk missiles at Houthi-controlled radar sites "in the Dhubab district of Taiz province, a remote area overlooking the Bab al-Mandab Straight known for fishing and smuggling."
In 2017, the United States sent a total of $599,099,937 of foreign aid to Yemen despite being a supporter of the Saudi led military intervention.
US Secretary of Defense James Mattis asked President Donald Trump to remove restrictions on US military support for Saudi Arabia. In February 2017, Mattis wanted to intercept and board an Iranian ship in the Arabian Sea to look for contraband weapons, which would have constituted an "act of war". In April 2017, Justin Amash, Walter Jones and other members of Congress criticized US involvement in Saudi Arabian military campaign in Yemen, highlighting that Al Qaeda in Yemen "has emerged as a de facto ally of the Saudi-led militaries with whom [Trump] administration aims to partner more closely".
In November 2017, US Senator Chris Murphy accused the United States of complicity in Yemen's humanitarian catastrophe."Congress Votes to Say It Hasn't Authorized War in Yemen, Yet War in Yemen Goes On ". The Intercept. 14 November 2017.
In December 2017, the Trump administration urged restraint in the Saudi military action in Yemen, as well as in Qatar and Lebanon.US to Saudis: Temper actions on Yemen, Qatar, Lebanon; Al Jazeera; 8 December 2017; https://www.aljazeera.com/news/2017/12/tillerson-saudis-measured-yemen-action-171208151146607.html
US bombs used by the coalition have killed Yemeni civilians throughout 2018, including a Lockheed Martin made bomb that struck a school bus in August, killing 51 people.
In the wake of Jamal Khashoggi's murder in October 2018, the US Secretary of State Mike Pompeo and the US Secretary of Defense James Mattis have called for a ceasefire in Yemen within 30 days followed by UN-initiated peace talks. Pompeo has asked Saudi Arabia and the UAE to stop their airstrikes on populated areas in Yemen. President of the International Rescue Committee David Miliband called the US announcement as "the most significant breakthrough in the war in Yemen for four years". The US continues its support of the Saudi-led intervention with weapons sales and intelligence sharing. On 10 November 2018, the US announced it would no longer refuel coalition aircraft operating over Yemen. On 13 December, the US Senate voted 56-to-41 to invoke the War Powers Resolution and end US military assistance to Saudi Arabia over alleged war crimes in Yemen, but the bill was not brought up in the US House.
Following the US Senate vote, the Pentagon presented a bill of $331 million to Saudis and Emiratis for US' support in the Yemen Civil War. The bill was split between $36.8 million for fuel and $294.3 million for US flight hours. The Pentagon stated that Saudi Arabia has not made any payments since the beginning of the war.
In April 2019, Trump vetoed a bipartisan bill which would have ended US support for the Saudi-led military intervention. With 53 votes instead of the 67 needed, the United States Senate failed to override the veto. The legal arguments and policies of the Obama administration were cited as justification for the veto. The US Deputy Assistant Secretary of Defense Michael Mulroy stated that US support was limited to side-by-side coaching to mitigate civilian casualties and if the measure had passed it would do nothing to help the people of Yemen and may only increase civilian deaths. Mulroy supported the United Nations' peace talks and he pushed the international community to come together and chart a comprehensive way ahead for Yemen. Writing in The Nation, Mohamad Bazzi argued that Mulroy's defence of US support as necessary to limit civilian casualties was false, and that "Saudi leaders and their allies have ignored American entreaties to minimize civilian casualties since the war's early days".
In the August 2020 report issued by the Office of Inspector General, it is said that the State Department watchdog detected that Secretary of State Mike Pompeo declared an emergency for selling arms worth billions of dollars to Saudi Arabia, the United Arab Emirates and Jordan, in compliance with legal requirements. However, the risks posed to civilian lives Yemen, with relation to the arms sale, wasn't thoroughly assessed at the time of declaring the emergency, the report states. The report also cited that the State Department's frequent approval of arms sale to the Gulf states, Saudi and UAE, fell below the limits of AECA.
On February 4, 2021, the new US President Joe Biden announced an end to the U.S. support for Saudi-led operations in Yemen but has backtracked on that goal and is considering returning to the Trump administration's designation of the Houthi rebels in Yemen as foreign terrorists.