Theresa May has said it was «legally and morally forthwith» for the UK to join air strikes against the Syrian regime to prevent «further gentle suffering».
She told MPs there was «clear evidence» the Assad government was behind the Douma chemical weapons jump.
The UK had «explored every diplomatic channel» in response but regrettably decided there was no alternate to «limited, carefully targeted action».
But Labour leader Jeremy Corbyn judged the action was «legally questionable».
Calling on Mrs May to publish the legal advice in full-bodied, Mr Corbyn said the government must be «accountable to this Parliament and not to the whims of this US President».
He questioned who was accountable for the attack, saying that while it was «highly likely» the Assad government was behind it, other groups had carried out similar attacks and weapons inspectors be required to continue their work.
Sites near Damascus and Homs were hit on Saturday by the US, French and UK in reply to the alleged chemical attack on Douma on 7 April.
Both Syria, which disputes any chemical use, and Russia, which provides military support to the Syrian oversight, have reacted angrily to the action.
UK prime ministers do not legally poverty to consult Parliament before launching military action, although they maintain done so since the 2003 invasion of Iraq.
Briefing Parliament, Mrs May held it was in the UK’s national interest to act — insisting that «we have not done this because President Trump attracted us to but because it was the right thing to do».
She said the use of chemical weapons could not be «normalised» in either Syria or somewhere else, insisting the attack was a «stain on humanity» and fitted the pattern of the regime’s aforesaid use of such weapons.
«No other circle could have carried out this attack,» she told MPs, adding that the Syrian specialists had reportedly attempted to «conceal the facts… supported by the Russians».
The military rejoinder, she insisted, was aimed squarely at degrading the regime’s capacity to carry out more «indiscriminate» attacks, rather than to try and topple the regime.
Addressing call ins for Parliament to have been given a vote, she said much of the wit on which the action was based could not have been shared with MPs and a nimble response was needed to protect the integrity of the operation and prevent further agony.
«We have always been clear that the government has the right to act speedily in the national interest,» she said.
«I am absolutely clear that it is Parliament’s dependability to hold me to account for such decisions but it is my responsibility as prime minister to deliver the goods a succeed these decisions.»
Returning to the United Nations to try and secure a Security Caucus resolution would have been futile, she said, and effectively fact Russia a «veto over British foreign policy».
Mr Corbyn accompanied for a new War Powers Act, saying the convention that Parliament should be consulted anterior to military action was «broken» and had to be replaced by a «legal obligation» to get the backing of MPs.
Self-willed to what Mrs May claimed, he said it was evident all «non-military means had not been pooped».
«There is no more serious issue then the life and death things of military action. It is right that Parliament has the power to support or hinder the government from taking planned military action.»
Commons Speaker John Bercow has indicated he is likely to reject the PM’s plea for a subsequent emergency debate in favour of one asked for by Labour MP Alison McGovern.
Any express in these debates would be largely symbolic and would mainly reasonable acknowledge that Parliament has had its say rather than give MPs the chance to formally approve or send someone away the air strikes themselves.
The SNP’s Westminster head Ian Blackford said for Parliament to be consulted about military action «after the when it happened» was simply not good enough.
«When we are talking about military sortie in a third country, that is a decision that Parliament should be winsome and not government itself,» he told BBC News. «That is what democracy is all around.»
Liberal Democrat deputy leader Jo Swinson said the decision had been entranced «behind closed doors» and much more scrutiny was needed of the targets behind it.
While the situation in Syria was «very serious», she said there was not the selfsame «acute urgency» for military intervention on humanitarian grounds as there had been in Libya in 2011.
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Downing Street published its legal case for its in the name of in the strikes, stating that the action was legally justified on humanitarian ranges.
On Saturday, the Ministry of Defence said eight Storm Shadow guided missiles had been launched by four RAF Tornados at a former missile base, 15 miles west of Homs.
It is ratiocination President Bashar al-Assad’s regime had been stockpiling materials habituated to to make chemical weapons there, it said.
There has been no confirmation of any civilian deads. The MoD has stated the facility was located «some distance» from «concentrations of civilian habitation».
The UK and US bear said the strikes were successful, with President Trump word to the wise the US is «locked and loaded» for further action if there are more chemical raids.
On Saturday, the UN Security Council rejected a resolution drafted by Russia, while all Nato team ups have given the military action their full support.