China has added its voice to Russian concerns over a proposed US missile defence system based in Europe, saying it could trigger an arms race.
Commenting on the US plans a spokeswomen for the Chinese foreign ministry said proposed interceptor shield had "aroused great concern and attention".
"China believes that the impact of a missile defence system on strategic defence and stability is not conducive to mutual trust of major nations and regional security," Jiang Yu told reporters.
"It may also give rise to a proliferation problem."
The missile shield involves placing a radar system in the Czech Republic and interceptor missiles in Poland - two Eastern European countries that were in formerly in the Soviet bloc during the Cold War era.
China has also expressed concerns at another US shield being built around Japan, intended to ward off potential missile threats from North Korea.
Beijing is concerned that the US might use the same system to shield Taiwan, the self-ruled island that China claims as a renegade province.
Over the weekend Vladimir Putin the Russian president warned that Moscow could take "retaliatory steps" if the European shield is realised.
Such steps, he said, could include aiming nuclear weapons at US military bases in Europe
Russia believes the shield in Eastern Europe is meant for it, and says it has no choice but to boost its own military potential in response.
The US argues the missile shield would easily be defeated by Russia's large military arsenal, saying the network is meant to protect NATO allies against missiles launched from what it calls "rogue states" such as Iran and North Korea.