China joined Russia on Tuesday in criticizing a US plan to build a missile defense system in Europe, saying the system could set off an arms race.

The White House plans to install a radar system in the Czech Republic and interceptor missiles in Poland - two Eastern European countries that were in the Soviet orbit during the Cold War era.

Chinese Foreign Ministry spokeswoman Jiang Yu said the plan had "aroused great concern and attention."

"China believes that the impact of a missile defense system on strategic defense and stability is not conducive to mutual trust of major nations and regional security," she said. "It may also give rise to a proliferation problem."

Russia perceives the shield as a direct threat and says it has no choice but to boost its own military potential in response. In some of his latest comments on the matter, Russian President Vladimir Putin warned that Moscow could take "retaliatory steps" including aiming nuclear weapons at US military bases in Europe.

The US says the network is meant to protect NATO allies against a missile launch from Iran, not Russia.

China and Russia improved relations dramatically in the 1990s and forged what they call a "strategic partnership."