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From 11 January to 24 February 2024, the US and UK have conducted four joint naval and air strikes against the Houthis in response to their ongoing attacks on shipping. The US has also conducted a series of separate actions.

Beginning in November 2023, the Houthis have been launching attacks against ships it says are linked to Israel, causing shipping to be diverted away from the Red Sea, hindering world trade and freedom of navigation.

The Houthis are one of several Iran-aligned armed groups in the Middle East, which also include Hezbollah in Lebanon and Shia militias in Iraq, who have been conducting attacks against Israel, Israeli-linked ships, and US forces and military bases since the Hamas assault on Israel on 7 October 2023. 

The 2024 strikes follow warnings by the UK Defence Secretary that the UK was prepared to use military force to stop the Houthi attacks and a UN Security Council Resolution in January 2024 demanding a halt to them.

This research briefing explains who the Houthis are, their recent attacks, the UK/US strikes and their legal basis, and the international response.

Who are the Houthis?

The Houthis are a Yemeni armed group, who in 2014 seized control of Yemen’s capital, Sana’a, marking the beginning of a multi-sided conflict in Yemen. The Houthis are in conflict with the internationally recognised Government of Yemen, which has been backed militarily by a Saudi-led coalition since 2015. The Houthis now control much of northern Yemen and the majority of its population. A ceasefire took place in 2022 and peace talks are continuing.

The Houthis are one of several armed groups that receive military, financial or other support from Iran. Analysts judge their relationship has become closer in recent years.

In response to the recent Houthi attacks, on 17 January the US announced it will designate the Houthis as a specially designated global terrorist group. The Houthis are not a proscribed terrorist organisation in the UK.

The United Kingdom, United States and UN Security Council also apply sanctions and arms embargoes against the Houthis, with new UK and US sanctions announced in January and February 2024.

Houthi attacks since October 2023

Following the Hamas assault on Israel on 7 October 2023, the Houthis said they would seek to support Hamas militarily and launched missile and drone attacks against Israel. In November, the Houthis said they would target Israeli-linked shipping in the Red Sea in response to Israeli military operations in Gaza. On 24 February 2024, the US said the Houthis had launched at least 48 attacks. It previously said Houthi-targeted ships had links to 55 countries.

The Kiel Institute for the World Economy, a German think tank, estimates that due to ships being diverted, container ship capacity in the Red Sea was 80% lower than expected in January 2024 (compared to 2017 to 2019 levels).

Launch of international maritime coalitions

In December 2023, the US announced an international maritime coalition, Operation Prosperity Guardian to support freedom of navigation. Over 20 countries, including the UK, are participating, but only one from the Middle East (Bahrain). The UK has also deployed three ships to the region. In February, the European Union also launched a separate defensive mission.

International statements on Houthi actions

On 10 January 2024, the UN Security Council adopted resolution 2722 (2024) which condemned the Houthi attacks, demanded they stop, affirmed the right to freedom of navigation, and emphasised the arms embargo (PDF) in place against the Houthis. China and Russia abstained and argued the US response risked escalating the Israel-Hamas conflict, where a ceasefire should instead be pursued. UK and US representatives supported the resolution.

Two statements have been issued by a series of states calling on the Houthis to halt their actions. In December 2023, 44 states, including the members of NATO and the European Union, “condemned Houthi interference” with freedom of navigation. A further statement was issued by 13 states on 3 January 2024, including the UK, United States, Bahrain, Germany and Japan. It said the countries “are determined to hold malign actors accountable for unlawful seizures and attacks” in the Red Sea.

US and UK attacks on Houthi sites in 2024

On 11 January, 22 January, 3 February, and 24 February, the UK and US conducted strikes against Houthi targets. The US has also conducted a series of separate strikes. Australia, Bahrain, Canada, Denmark, the Netherlands, and New Zealand provided non-operational support for the US/UK actions. These strikes are separate from Operation Prosperity Guardian.

The UK Government said these the strikes are “limited, necessary and proportionate in self-defence”. Speaking in the Commons, the Prime Minister, Rishi Sunak, said the UK acted “in self-defence”, following Houthi attacks on Royal Navy ships, “consistent with the UN charter, and to uphold freedom of navigation”. On 26 February, the Defence Secretary said that the UK had “seen no evidence” that RAF strikes had caused civilian casualties.

On 23 January, the Prime Minister set out four priorities for the UK in the Red Sea: 1) diplomatic effort to support de-escalation 2) enforcing the arms embargo against the Houthis 3) implementing new sanctions 4) continuing to provide aid to Yemen and support a political solution to the conflict.

The United States has said its actions were “defensive” in nature and focused on military targets and used “precision-guided munitions to minimize collateral damage”. Both countries emphasised their aim “remains to de-escalate tensions and restore stability in the Red Sea”.

What was parliament’s role and response?

The Commons was not sitting when the US/UK strikes occurred on 11 January. It was not recalled, though the Scottish National Party, Liberal Democrats and Plaid Cymru argued Parliament should have been consulted. The Prime Minister gave a statement to the Commons on the first sitting day after the strikes, 15 January 2024. He also gave a statement on 23 January and the Commons debated, but did not vote, on the Red Sea situation on 24 January.

Defence Minister, James Heappey, said the Government had to act on 11 January “based on the military, strategic and operational requirement” and this informed the operation’s timing. Defence Secretary, Grant Shapps, also said the Government “need[ed] to be able to act” and the parliamentary process “would potentially degrade the quality of the operation itself”.

The Labour Leader, Keir Starmer, backed both sets of strikes to “reinforce maritime security in the Red Sea”. The SNP leader in the Commons, Stephen Flynn, called on the Government to avoid “escalation that leads to further regional instability” but backed the actions. Liberal Democrat leader, Sir Ed Davey, said the party backed “limited strikes” but called for a Commons vote.

As described in the Commons Library research briefing, Yemen airstrikes: Parliament’s role in approving military action, Parliament has no legally established role or requirement to be consulted. In 2011 the Government acknowledged the emergence of a convention that before military action took place the House of Commons would have the opportunity to debate the matter, except in an emergency. As set out in the briefing, the approach to consulting Parliament has, however, been inconsistent.

Update log

29 January 2024: Added information on new UK/US sanctions

6 February 2024: Added information on most recent UK/US strikes 

1 March 2024: Added information on most recent UK/US strikes and sanctions

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