Britain could start bombing ISIS targets in Syria within days after David Cameron announced he will push ahead and hold a House of Commons vote on authorising military action.
The prime minister had previously said he would not allow parliament to vote on the issue unless he was confident he had sufficient support for airstrikes, suggesting he is now sure enough Labour MPs will back his plan to intervene in Syria.
The vote will be held on Wednesday, meaning the first attacks could be launched by the end of the week. Britain is already carrying out raids on ISIS targets in northern Iraq.
In a statement on Monday night Cameron confirmed he will ask cabinet to back intervention in the country: "As I said last week, the decision to take military action is one of the most serious a prime minister can make. Tomorrow, I will be recommending to the cabinet that there be a debate and vote in the House of Commons on a motion to participate in coalition airstrikes against ISIL in Syria."
The prime minister said the attacks would be justified because the Islamist organisation threatened Britons: "ISIL poses a very direct threat to the United Kingdom – and as we have already seen in Iraq, British airstrikes can play a key role in degrading them; but they are only part of a comprehensive strategy for Syria.
"This strategy must include the international community working together to find a political solution to the turmoil in Syria; a continuation of our extensive humanitarian efforts; and a clear commitment to post-conflict reconstruction of Syria."
Earlier, Labour leader Jeremy Corbyn, who strongly opposes military intervention, was forced to offer Labour MPs a free vote on the issue following displays of support for bombing from leading members of his shadow cabinet.
The SNP has said it will not support raids, while the Lib Dems are thought to be considering backing the prime minister's plan for intervention.