China's destruction of a defunct weather satellite is a dramatic display of the ancient battering-ram strategy brought up to date with 21st century knowhow.

Security experts believe China launched a medium-range KT-1 ballistic missile to intercept the satellite, which struck with sufficient force to obliterate it without the need for an explosive warhead. To prove they had the capability to track, target and destroy an object in space, it was the easiest solution: Chinese officials would have known the exact position, speed and altitude of the satellite.

The rocket would have been launched and targeted using a ground-based tracking station to guide it.

Once on the right trajectory, experts believe the rocket will have switched to on-board radar and possibly infra-red sensors to home in.

The satellite occupied a region of space just over 500 miles high called low-Earth orbit. It is lowest of the satellite orbits available and is favoured by the military for spy satellites, since it gives them the best possible images of the ground.

Despite picking off one of its lowest satellites in the test, China has developed two longer-range missiles, known as the KT-2 and KT-2A, which carry boosters and are believed to be capable of reaching more critical satellites in higher orbits.

The GPS satellites that are crucial for smart weapons, such as cruise missiles, orbit at about 8,000 miles above Earth, and broadband communications satellites orbit at around 22,000 miles in geostationary orbits. Together, GPS and communications satellites are Achilles' heels of modern warfare.

During the last Iraq war, 83% of communications between allied forces were sent via satellites.

"It would have an enormous impact if a country were able to destroy those satellites," said Pat Norris, chair of the Royal Aeronautical Society's Space Group.

China's destruction of a satellite is not a first. Both the US and Russia developed developing anti-satellite technology in the late 1950s, although early air-launched missiles were abject failures. The first successful satellite strike was in 1985 when a US missile destroyed a satellite called Solwind.

Tests of missile-based anti-satellite systems was suspended shortly after because another danger was apparent -the debris threatened other satellites and astronauts directly. A study by the US Union of Concerned Scientists found that the Chinese test would have produced about 800 fragments larger than 10cm and 40,000 fragments between one and 10cm.

The US has instead shifted its efforts to new technologies. Plans exist to develop space-based "directed energy weapons", usually lasers, which could target satellites from space. A project favoured by Donald Rumsfeld, the former US defence secretary, is known as "rods from the Gods", in which metal rods are dropped from space, building up kinetic energy on the way down, is still under consideration. Other technologies being investigated by the US include louvres for satellites, which would defend against blinding lasers used to dazzle satellites.