The thought of Donald Trump as space commander-in-chief, whizzing around the Milky Way, zapping alien invaders and conquering new worlds, is both comical and terrifying. Before they began exchanging love letters, the US president ridiculed his North Korean counterpart, Kim Jong-un, as “little rocket man”. With his relaunch last week of US space command (SpaceCom), terrestrial Trump has appropriated the title for himself.

While this may be a big step for the man in the White House, it’s a giant leap backwards for mankind. Fresh from his bungled attempt to expand America’s frontiers by buying Greenland, Trump is now suggesting the US has a right to colonise outer space, treating it as a free-fire zone for unlimited superpower competition in “the next war-fighting domain”. Trump has watched too many repeats of Independence Day. The universe does not belong to America.

The 1967 Outer Space Treaty clearly states that space is free for exploration and use by all nations and that no nation may claim sovereignty over outer space or any celestial body. It also prohibits the deployment of nuclear weapons and other weapons of mass destruction. Unusually, this is one international treaty the US has actually signed and ratified. It is bound to honour it.

While Trump and his Pentagon space cadets may argue they do not intend to assert US sovereign control, their stated intention to establish exclusive, unchallengeable American dominance amounts to much the same thing. Unfortunately, the treaty does not prevent military activities in space, military space forces or weaponisation – and it is these objectionable aims that lie at the heart of SpaceCom’s new mission.

According to Gen John Raymond, SpaceCom commander, being top dog in space is a “vital [US] national interest” that is threatened by rivals, notably China and Russia. “The scope, scale and complexity of this threat... is real and concerning,” he said. “Although space is a war-fighting domain, our goal is to actually deter a conflict extending into space. The best way I know to do that is to be prepared to fight and win... We are the best in the world at space.”

How about best in space at space? That would be more impressive. It’s odd the way the American republic finds it necessary to constantly assert its superiority. It smacks of insecurity. And why is the US military mind so deaf and blind to history that it cannot recognise the old, cyclical “threat=counterthreat=bigger threat” thinking that gave us Vietnam and the insanely dangerous US-Soviet nuclear arms race?

Unable or unwilling to learn from the past, the generals have found a new battlefront – and in Trump someone only too happy to encourage aggressive behaviour. What do they imagine will happen next? Other countries, alarmed by this projection of heavenly hegemony, will seek to match or surpass US capabilities. Like space itself, the potential for ruinously destructive rivalry is infinite.

It is entirely reasonable for governments to want to protect satellite communications and navigation systems from, say, ground-based interceptor missiles and electronic warfare. It is legitimate to aim to be “a leading player in space”, as Penny Mordaunt, the former UK defence secretary, said in July in setting out British objectives. It is undoubtedly true that space presents unique opportunities for potentially commercially valuable scientific and medical research, innovation, exploration and civilian travel.

But the way to ensure space does not become another “war-fighting domain” is not to embark on a weaponised race for national advantage. It is not to join US military-led “space deterrence” initiatives, such as Operation Olympic Defender, as the UK plans to do. To avoid the militarisation of space and the consequent risk of future conflict, all concerned countries should work together to create an international space authority tasked with enforcing binding new rules, embodied in an updated, UN-approved treaty. Will they do so? Watch this space.