The USS Lake Erie launches a missile in February 2008 to destroy a defunct spy satellite. Photo: US Navy
When China destroyed one of its own satellites in space six years ago, it alarmed many other Asia-Pacific countries that had invested heavily in orbiting satellites for telecommunications, earth observation and scientific research.
China's action caused particular concern to the United States, Australia, Japan, India and other nations that used satellites for military purposes, including voice and data communications, surveillance, precise navigation and guidance of bombs and missiles.
In 2008, just over a year after the Chinese test, the US fired a modified ballistic missile defence rocket from a warship to shoot down a malfunctioning US spy satellite about 250 kilometres above the Pacific Ocean. The US said the operation was essential to prevent the bus-sized craft and its toxic fuel from crashing back to Earth, possibly causing death, injury and damage.
While space has long been used for military reasons, it is not yet a place for stationing weapons, a development that will create a highly volatile frontier of international rivalry and geo-political tensions.
Some Western and Asian analysts are concerned that China may be planning another test of a weapon designed to destroy or damage a satellite or interfere with its functioning.
The Global Times, an often-nationalistic newspaper published by the People's Daily, the flagship of the ruling Chinese Communist Party, said in an editorial this month that the US advantage in space was "overwhelming". It pointed out the US had so far refused to negotiate on a treaty to outlaw arms in space first proposed by China and Russia in 2008.
The US said such a treaty could not be verified and that the US needed freedom of action in space. The Global Times said China therefore needed "an outer space trump card" by showing it could threaten US superiority.
The newspaper added that, "against this background, it is necessary for China to have the ability to strike US satellites. This deterrent can provide strategic protection to Chinese satellites and the whole country's national security."
Is the world on the verge of a space warfare era in which weapons are based in space with the capability to attack targets there or on the ground?
The US Department of Defence, in its 2012 report to Congress on Chinese military developments, accused China of "developing a multi-dimensional program to limit or deny the use of space-based assets by adversaries in times of crisis or conflict".
China's test, in January 2007, of an anti-satellite weapon to shoot down an ageing Chinese weather forecasting satellite in low earth orbit about 850 kilometres out, showed it had the capability to strike spacecraft in the most widely used satellite traffic belt.
Nearly half of the world's estimated 1020 operational satellites are in low earth orbits, those below 2000 kilometres. They include spy satellites that need to be relatively close to the surface of the land or sea to take high-resolution photographs and other images that are of intelligence and military value.
The Chinese test ended a long period of restraint by the main space users. Only two nations, the former Soviet Union and the US, had previously destroyed spacecraft in anti-satellite tests. America's last test was in the mid-1980s.
As it turned out, China's 2007 anti-satellite weapon test was not its first, or the last. In January 2010, China fired a similar rocket to the one it used in 2007, but this time as a missile defence test. The intercept occurred at a much lower altitude, of about 250 kilometres, than the 2007 test and targeted a dummy warhead launched by a ballistic missile instead of a satellite in orbit.
However, there is no technical difference between anti-satellite-weapon interceptors and missile defence interceptors that work above the atmosphere in outer space. For space treaties, the atmosphere is defined to end and outer space to begin at an altitude of 100 kilometres above sea level.
A US State Department cable on China's 2010 test was published by WikiLeaks in March 2011. According to the cable, China carried out flight tests of its direct-ascent anti-satellite interceptor rocket in 2005 and again in 2006.
The Pentagon said that, in addition to the direct-ascent anti-satellite weapon that the Chinese military used in 2007 to destroy a satellite, China's counter-space capabilities included jamming, laser, microwave and cyber weapons.
Its 2012 report to Congress said that, over the past two years, China had conducted increasingly complex, close-proximity operations between satellites, while offering little in the way of transparency or explanation.
China's 2007 test also raised international concerns because the wreckage left more than 3000 pieces of space debris that were a hazard to operational satellites. Both the satellites and the debris orbit at very high speeds, increasing the risk of collision.
China plans to put many more satellites into low, medium and high orbit above Earth, for civilian and military purposes, consolidating its place with the US and Russia as one of the world's three leading space powers.
The 1967 Outer Space Treaty bans the stationing of weapons of mass destruction in space but not anti-satellite weapons.
In an effort to break the deadlock between the US on the one side and China and Russia on the other, the European Union has drawn them and about 40 other countries into negotiations on an international code of conduct for outer-space activities.
The EU wants to finalise the voluntary code, which would not be legally binding, this year. The aim is to limit further space debris, improve international co-operation and create a "peaceful, safe, and secure outer-space environment".
Whether such a code could, by itself, prevent an arms race in space is doubtful.
However, as China's reliance on orbiting satellites grows to match that of the US and Russia, their mutual interest in stability may prevent conflict in outer space, just as fears of mutually assured destruction have helped to prevent nuclear warfare since 1945.
Michael Richardson is a visiting senior research fellow at the Institute of South East Asian Studies in Singapore.