Jeremy Corbyn has been criticised after condemning UK and US joint strikes on Houthi rebels.
He slammed last night's measures as a "reckless act of escalation", arguing that it is "utterly disgraceful" for Parliament not to have been consulted.
The former Labour leader asked: "When will we learn from our mistakes and realise that war is not the answer?"
Britain joined the US in unleashing targeted strikes against military facilities in Yemen last night in response to "reckless actions" of Houthi rebels in the region.
Jeremy Corbyn has been criticised after condemning UK and US joint strikes on Houthi rebels
PA
Action was taken after weeks of disruption to international shipping in the Red Sea.
Other left wing Labour MPs echoed Corbyn's remarks, with MP Apsana Begum slamming the attacks as "dangerously provocative".
She called for “de-escalation and peace-building in the region”.
Labour MP for Leicester East, Claudia Webbe, wrote on X: "Stop the war. Stop bombing Yemen. Recall Parliament now".
Brendan Clarke-Smith, the Conservative Party's deputy chairman, accused Corbyn of defending an "unpleasant group of bad actors".
Meanwhile, a member of Labour's national executive committee, Abdi Duale, said the former Labour leader "always finds himself supporting the wrong side".
Clarke-Smith told the Express: "If there’s a despotic regime or an unpleasant group of bad actors then you can always guarantee that he will spring into action to defend them ahead of his own country.
"Let’s not forget that Sir Keir Starmer twice tried to make this man Prime Minister.
"Just imagine for one moment that had happened and the resulting effect on British security and defence capabilities.”
Duale added: "Taking action against a terrorist group that’s attacked UK Vessels is in our country’s self defence, Jeremy.
"Wouldn’t expect a man who always finds himself supporting the wrong side to acknowledge that."
Last nights strikes came in response to a series of attacks on shipping routes in the Red Sea by Houthi rebels.
Houthi officials have reacted with fury to the UK and US' response, calling the strikes "barbaric".
The US Air Force said American and British forces struck more than 60 targets in 16 locations.
The MoD said "particular care was taken to minimise any risks to civilians” when planning the strikes on Houthi targets in Yemen.
In a chilling threat of further retaliation, high-ranking Houthi official Ali al-Qahoum added: "The battle will be bigger…. and beyond the imagination and expectation of the Americans and the British."
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The Cabinet was informed of the plans in a meeting called last night by No10. In an unusual move, the Government also briefed Sir Keir Starmer and shadow defence secretary John Healey.
In a statement released after the bombings, Prime Minister Rishi Sunak said: "In recent months, the Houthi militia have carried out a series of dangerous and destabilising attacks against commercial shipping in the Red Sea, threatening UK and other international ships, causing major disruption to a vital trade route and driving up commodity prices.
"Their reckless actions are risking lives at sea and exacerbating the humanitarian crisis in Yemen.
"Despite the repeated warnings from the international community, the Houthis have continued to carry out attacks in the Red Sea, including against UK and US warships just this week. This cannot stand. The United Kingdom will always stand up for freedom of navigation and the free flow of trade.
"We have therefore taken limited, necessary and proportionate action in self-defence, alongside the United States with non-operational support from the Netherlands, Canada and Bahrain against targets tied to these attacks, to degrade Houthi military capabilities and protect global shipping.
"The Royal Navy continues to patrol the Red Sea as part of the multinational Operation Prosperity Guardian to deter further Houthi aggression, and we urge them to cease their attacks and take steps to de-escalate."