Theresa May says she has 'responsibility as Prime Minister to make decisions' and that she 'will make them'.
The UK leader has addressed MPs in the House of Commons over her decision to launch airstrikes in Syria without parliamentary approval.
The airstrikes were in response to a chemical weapons attack in Syria last week.
She told MP's 'we can't go back to a world where chemical weapons are normalised' and the' fact that such an atrocity can take place is a stain on our society.'
Theresa May explained why she didn't recall parliament before making the decision to join the US and France in the military action;
"The speed with which we acted was essential in co-operating with our partners to alleviate further humanitarian suffering and to maintain the vital security of our operations
This was a limited, targeted strike on a legal basis that has been used before and it was a decision which required the evaluation of intelligence and information, much of which was of a nature that could not be shared with parliament."
Today's statement from the Prime Minister @theresa_may on Syria has started. Watch https://t.co/DyDVlgvJVq pic.twitter.com/4Wzkpt3oSY
— UK House of Commons (@HouseofCommons) April 16, 2018
Addressing MPs, Theresa May also said Russia's veto on a UN resolution for an independent investigation left no other option.
Opposition parties argue that Parliament should have been consulted first.
Labour leader Jeremy Corbyn faced shouts of "shame" from Tory MPs as he questioned the Theresa May's role in airstrikes on Syria.
He told the Commons that her statement to the House shows that she should be accountable to Parliament - not to the whims of the U.S. President.
The PM insists diplomacy was no longer an option.
But Mr Corbyn says there is no more serious issue than the life and death matters of military action.