U.S. warplanes flew combat missions from a UK ship this week, marking the first time American warplanes went into combat from another nations carrier since World War II.

The mission, according to a statement from the UK government, was against ISIS.

Eighteen UK and U.S. F35B jets were on board the HMS Queen Elizabeth. The mission, according to the UK government, is the largest concentration of maritime and air power to depart the UK in a generation, and the vessels first operational deployment.

The mission was also the first operational deployment for HMS Queen Elizabeth.

HMS Queen Elizabeths first missions against Daesh will be remembered as a significant moment in the 50-year lifespan of this ship, Commodore Steve Moorhouse, commander of the United Kingdom Carrier Strike Group, said in a statement, referring to ISIS by its Arabic acronym.

Captain James Blackmore, the commander of the Carrier Air Wing, wrote in a statement that the mission was the first time a U.S. aircraft flew from a foreign carrier since the HMS Victorious in the South Pacific in 1943.

The level of integration between Royal Navy, Royal Air Force and US Marine Corps is truly seamless, and testament to how close weve become since we first embarked together last October, Blackmore added.

A U.S.-led military coalition in January killed the top ISIS leader, in what was an airstrike meant to beat back a resurging terror campaign following a double suicide bombing in Baghdad.

The leader, Jabbar Salman Ali Farhan al-Issawi, 43, known as Abu Yasser, was killed in a joint mission with U.S. and Iraqi forces.