The US has issued a worldwide travel alert to its citizens, citing terrorist threats from Isis, al-Qaeda, Boko Haram and "other terrorist groups".
The alert from the US State Department urges US citizens to exercise caution in public places and during holidays and public events.
French President Francois Hollande will meet Barack Obama at the White House on Tuesday to discuss the fight against so-called Islamic State.
David Cameron will hold talks with Francois Hollande on the fight against so-called Islamic State on Monday.
The Prime Minister is in Paris to meet the French President, 10 days after the capital city was terrorised by a series of deadly attacks.
France has stepped up its campaign against IS since the attacks, which left 130 people dead.
The meeting comes after the UN Security Council called on all "able states" to join the fight against IS militants in Syria and Iraq and redouble their efforts to prevent further attacks by the group.
France and the US have agreed to step up airstrikes in Syria and Iraq to target IS in the wake of the Paris attacks.
Britain will do "all in our power" to support France in the fight against IS following the Paris terror attacks, David Cameron said.
The United Nations Security Council agreeS to intensify efforts to 'eradicate' Islamic State in the wake of the Paris terror attacks.