UK Defense Secretary Michael Fallon has appealed to the MPS to reconsider the case for airstrikes in Syria.
"I am asking MPs particularly to reflect on the fact that the streets of Britain at the moment are being kept safe by American, Australian and French aircraft striking at the heart of ISIL in north-east Syria from where ISIL is organised and directed," he said.
He went on saying that it is "morally indefensible" for Britain to rely on other countries to tackle the ISIL threats in Syria.
British MPs rejected possible UK military action in Syria in 2013.
He also dismissed reports a second vote has been dropped, saying it would be held when "we are pretty sure we can win".
"ISIL is a very direct threat to us in Britain. We've had 30 British holidaymakers slaughtered on a beach in Tunisia, and it's not right morally to rely on French or Australian or American aircraft to keep our streets safe," he added.
Last year, Parliament approved UK airstrikes against ISIL also known as Daesh targets in Iraq, with the government winning by 524-43.
"If we're serious about tackling ISIL, in the end we have to be prepared to strike at ISIL headquarters, which is in Syria, not Iraq," he said.
Fallon said the government plans to hold a series of intelligence briefing for MPs over the next few weeks on the RAF campaign as part of efforts to build a political consensus to expand its mission.
This comes as the influential Foreign Affairs Committee urged Prime Minister David Cameron not to press ahead with a vote on UK air strikes against ISIL in Syria.
Opposition leader Jeremy Corbyn has said there had to be a political solution and he did not believe that "more bombing is going to help in this".