The Trump administration has celebrated the first birthday of the US Space Force by announcing that its members will be known as guardians. Vice President Mike Pence made the announcement at a celebratory event tracing the development of the newest branch of the military over the past year. "It is my honour, on behalf of the president of the United States, to announce that henceforth the men and women of the United States Space Force will be known as guardians," Mr Pence said on Friday. "Soldiers, sailors, airmen, Marines and guardians will be defending our nation for generations to come."