The US has admitted deploying weapons in space and China is sounding the alarm

The US has confirmed it has stationed arms in orbit around the Earth, in a move China warns could turn space into a "battlefield".

The revelation by Washington confirmed an open secret but the timing of the announcement risked exacerbating tensions with Beijing and the risk of a weapons race in space.

The announcement marked a new stage in the major powers' rush for military space capabilities, driven by rapid technological advancements but lacking a comprehensive legal framework.

Here's what we know about the US's latest move and what it could mean for the future.

What are the US's capabilities?

The US statement did not provide concrete details about what weapons are deployed in space and how many.

"Space control encapsulates the mission areas required to contest and control the space domain — employing kinetic and non-kinetic means to affect adversary capabilities," the statement said.

"These capabilities can be employed for offensive and defensive purposes," it added.

Non-kinetic means could include lasers to blind satellites, or even electromagnetic or cyber jamming of their data links.

Why does the US want weapons in space?

For Washington, both Russia and China — its two main geopolitical rivals — pose potential threats to US interests in space.

China "develops and operates space and counterspace capabilities as part of a military modernization strategy," according to the US Space Force.

Russia, meanwhile, "views space as a warfighting domain and believes space supremacy will be a decisive factor in future conflicts", it said.

The militarisation of space is as old as the space race itself.

As soon as the USSR's Sputnik was launched into orbit as the first probe in space in 1957, Washington and Moscow began exploring ways to both arm and destroy satellites.

India in March 2019 said it had destroyed a low-orbiting satellite, following in the footsteps of Russia, China and the US, in a missile test that proved the nation was among the world's most advanced space powers.

How has China reacted?

China's foreign ministry has already expressed its opposition to the move, warning against the "weaponisation of outer space, turning it into a battlefield, as well as an arms race there".

"The US has on-orbit space control weapons capable of defending the Joint Force against hostile adversary action," a US Space Force spokesperson said in a statement that did not provide specifics on the weapons.

Song Zhongping, an independent military commentator based in Hong Kong and former Chinese army instructor, told AFP the announcement was "no surprise at all" as the fact that the US possesses such weapons "has long been an open secret".

"The only difference is that the US used to keep it ambiguous, whereas now it has gone public, which shows that Washington is no longer trying to hide it,"

he added.

"China will not stand by and do nothing," he warned, noting Beijing already has its own space station in orbit.

"Whether China deploys weapons in space will depend entirely on whether the United States moves in that direction," he said.

The Wall Street Journal said Beijing supplied Iran with satellite imagery that enabled Tehran to precisely target military facilities and kill US service members in Jordan in July, a claim China has denied.

Russia, meanwhile, called for space to be kept "free of any weapons".

Can weapons in outer space be regulated?

The biggest worry was once about nuclear weapons in space, but the superpowers and other countries signed the Outer Space Treaty in 1967, banning weapons of mass destruction in orbit.

Since then, Russia, the United States, China and India have explored ways to fight in space outside of that treaty, including by targeting rivals' satellites, which are key for military communications, surveillance and navigation.

"There is a regulatory vacuum because Article 4 of the 1967 treaty only forbids weapons of mass destruction and nuclear weapons in orbit," said space law expert Laetitia Cesari.

She said the topic would likely be on the agenda at the next UN disarmament meeting in November.

"Moscow and Beijing have been wanting to work for about twenty years on a treaty to prevent the placement of weapons in space," while "Western states are trying instead to work on the notion of responsible behaviour," Ms Cesari said.

The US announcement "will likely give impetus to the restrictive approach that Moscow and Beijing are pushing for," she said.