On Thursday, President Donald Trump participated in a ceremony reestablishing the U.S. Space Command after 17 years. The program was eliminated in 2002 after 9/11 shifted parts of the government’s focus to combating terrorism. But the president revived it amid new concerns about U.S. satellites that are susceptible to anti-satellite weapons from countries like China and Russia. The command will allow satellite-based navigation and communications for troops in the field. It will also be able to warn the U.S. when missiles are launched abroad. During the ceremony, the president spoke about the national security and defense the Space Command will ensure. “Just as we have recognized land, air, sea and cyber as vital war-fighting domains, we will now treat space as an independent region overseen by a new unified geographic combatant command,” President Trump said.