Both Russia and China have developed "space stalker" satellites that can be manipulated to physically interfere with others.

Last year a US general made an ominous revelation: two Russian satellites in orbit were stalking a US spy satellite high above the earth.

It wasn't clear if the Cosmos satellites could attack USA-245, an American surveillance spacecraft.

"It has the potential to create a dangerous situation in space," said General Jay Raymond, head of the Pentagon's Space Command.

The incident passed, but it marked a new stage in the mounting arms race in space, where potentially bomb-armed satellites, laser-shooting spacecraft and other technologies have moved from science fiction to reality.

The stakes were made clear Monday when Russia launched a missile from Earth and blasted to pieces one of its satellites in a show of force.

NATO Secretary General Jens Stoltenberg called the act "reckless."

"It demonstrates that Russia is now developing new weapons systems that can shoot down satellites," he said at a meeting Tuesday with EU defence ministers.

The militarization of space is as old as the space race itself -- as soon as Sputnik was launched into orbit in 1957, Washington and Moscow began exploring ways to both arm and destroy satellites.

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

Since then, Russia, the United States, China and even India have explored ways to fight in space outside of the treaty.

That competition today focuses on destroying a rival's satellites, which are increasingly essential to every advanced military for communications, surveillance and navigation.

In 1970, Moscow successfully tested a satellite loaded with explosives that could destroy another satellite in orbit.

The US answered back in 1983, when then-president Ronald Reagan announced his ambitious Strategic Defence Initiative -- the "Star Wars" program promising precision-guided anti-missile missiles and satellites emitting laser beams or microwaves -- to make the US militarily superior.

Much of the technology envisioned was unfeasible. But in a landmark move, the Pentagon used a missile to destroy a failed satellite in a 1985 test.

Since then, rivals have sought to show they had the same targeting skills: China in 2007 and India in 2019.

After trying for some time, Russia's successful shoot-down on Monday was unsurprising for many experts.

"The Russians did not need to detonate the satellite to demonstrate that they had the ability to do so," said Isabelle Sourbes-Verger, a space expert at France's National Centre for Scientific Research.

It was a demonstration "that if necessary in asymmetric responses, Russia will not permit the United States to be the only one in control of space," she said.

Countries are intensely secretive about their military space activities, and because many of the technologies involved are dual-use -- useful for both civilian and defense purposes -- their capabilities are not fully clear.

But the race is such that by 2019, the year the Pentagon established its Space Force, it believed that Russia and China had the potential to surpass the US.

"Maintaining American dominance in that domain is now the mission of the United States Space Force," said then-Secretary of Defence Mark Esper.

The race has evolved from the idea of killing satellites with missiles, or kamikaze satellites, to finding ways to damage them with laser or high-powered microwave weapons.

Both Russia and China have developed "space stalker" satellites that can be manipulated to physically interfere with others, according to Brian Chow, an independent space policy analyst who spent 25 years at the Rand Corp think tank.

With robotic arms, "they can just stalk the opponent satellite and move it somewhere else, or bend an antenna" to render it useless, said Chow.

Those satellites remain few, but Russia's deployment of two to menace the US satellite in 2020 shows the technology has arrived

China and the United States both have ultra-secret programs of small, reusable, robotic, winged spacecraft which could potentially be used with weapons and damage a rival's satellites.

Countries are also developing surface-based weapons to jam and spoof satellite signals, and to use directed energy to damage them.

The US Defence Intelligence Agency said in 2019 that China had five bases with ground-based lasers that could be used to disable enemy satellites.

"Every satellite that passes over China would be subject to attack," said Chow.