The U.S. military will need to be prepared to fight not only in Earth's orbit but also in orbit around the moon, President Donald Trump's top military advisor said on Wednesday. 

The comments were made at the Air and Space Forces Association conference in Oxon Hill, Maryland. On Monday, the U.S. revealed for the first time that it has a weapon in orbit around the Earth. 

On Wednesday, Gen. Dan Caine, chairman of the Joint Chiefs of Staff, told service members and industry figures at the conference that the U.S. military "is prepared to fight, endure and win ... from the seabed to cislunar space," The Washington Sun reported. 

"Cislunar" refers to the region of space located between the Earth and the Moon's orbit. 

Lt. Gen. Gregory Gagnon, head of the force’s Combat Forces Command, told reporters that Space Force, the newest military service that President Donald Trump created in 2019, is preparing to fight in space and around the moon because "humanity is advancing deeper into space," and it's the job of Space Force to "defend U.S. interests."