France will begin reconnaissance missions over Syria on Tuesday and could launch air strikes against ISIS militants in the country, President Francois Hollande said on Monday.
France until now had only taken part in air strikes against ISIS in Iraq because it feared strikes against the group in Syria could strengthen Syrian President Bashar Assad.
"We have proof that attacks have been planned from Syria against several countries, notably France," Hollande told a news conference.
"My responsibility is to ensure that we are informed as much as possible on the threats to our country ... so I have asked the defense minister that from tomorrow reconnaissance flights begin over Syria that will enable us to consider air strikes against ISIS."
France was poised to join air strikes on the Assad regime in Syria in 2013, before President Barack Obama unexpectedly backed off the plan.
Hollande said ISIS had cemented its position in Syria over the last two years and that Paris now needed to know exactly what was happening on Syrian soil.
Britain is also moving closer to taking military action, with reports saying a parliamentary vote could take place next month to authorize the bombing of ISIS targets.
Prime Minister David Cameron was defeated in parliament in 2013 when he sought to join the proposed action then. Hollande ruled out any ground intervention in the country, saying it was for Syrians and regional states to do the work on the ground.
He also reiterated that the only solution to the Syria crisis was through a political transition that would see Assad leave power "at some point or another."
"Assad is responsible for the situation in Syria. He fired on his people, he bombed civilians. He used chemical weapons and refused to talk to opponents," Hollande said.