Passengers were evacuated from a plane shortly before take-off at Reagan National Airport in Washington, D.C. after suspicious crew members called police.
Two people on board were removed by authorities and sniffer dogs were brought on to the jet on Sunday afternoon.
The flight, bound for Boston, took off two hours later and the two passengers detained were released by authorities.
The incident happened two days after the terrorist attacks in Paris, in which 129 people died. Following the attack, major cities in the U.S. and around the world are on heightened alert.
A video, which is yet to be verified as authentic, claims ISIS will target Washington as well as other key cities, including London and Rome.
Washington’s police department has deployed extra officers to high-profile locations in the city – including the government’s Capitol complex.
Paris’ major tourist attractions, including the Louvre, the Eiffel Tower and many museums remain closed today as the country entered the third day of mourning following the attacks.
Although public transport is operating as usual, authorities have told travellers to Paris to expect longer procedures as police controls are stepped up at airports and at Paris’ key train stations, including Gare du Nord.
The American Society of Travel Agents (ASTA) president and CEO Zane Kerby said: "We stand ready to assist our 35 ASTA members who are based in and around the Paris area any way we can. With heavy hearts we pray for peace and the safety of our friends in France and those affected by this horrific attack."
A false alarm near the Eiffel tower led to panic with heavily-armed guards evacuating the area.
