The declaration came a day after President Vladimir Putin, eyeing nationalist votes for elections next month, promised to equip his armed forces with a new generation of long-range weapons matching those of the United States.
First Deputy Chief of Staff Colonel-General Yury Baluyevsky said that during large-scale military exercises on Wednesday, Russia had test-launched a missile system that could manoeuvre in mid-flight, allowing it to dodge defences.
"The test carried out yesterday confirmed that we can build weapons which will render any anti-missile system defenceless against an attack by Russia's strategic forces," he told a news conference.
"It's part of our unilateral response to the creation or future creation of a missile defence system by any state or bloc of states," he said.
"We can build weapons which will render any anti-missile system defenceless against an attack by Russia's strategic forces"
Col-Gen Yury Baluyevsky,
Russian First Deputy
Chief of Staff
Moscow and Washington agreed not to develop large-scale missile defences in the Cold War, but US President George W Bush pulled out of the treaty in 2002, saying the United States had to ward off threats from terrorists and "rogue states".
Washington appeared unperturbed by the Russian missile test.
"I don't think it has any impact on US-Russian relations. They've got to design a missile force that they think is sufficient for deterrence, just like we do," Air Force General Richard Myers, chairman of the Joint Chiefs of Staff, told reporters in Washington.
Baluyevsky said Russia was not opposed to missile shields and reiterated remarks by President Putin, who said on Wednesday that Russia was not too worried about the US plan and cooperation between the two countries was good.
Russia's manoeuvres have not gone entirely smoothly over the last week.
A Russian ballistic missile self-destructed after a failed test launch from a submarine in the Arctic north on Wednesday.
On Tuesday, two ballistic missiles failed to take off in a test on another nuclear submarine.
US defensive shield
The US defensive shield remains in its early stages. The initial system, being built by Boeing, Raytheon, Lockheed Martin and Orbital Sciences, is designed only to protect against a limited attack.
Critics of the US effort, budgeted at $50 billion over the next five years, worry it could trigger an international arms race to overwhelm anti-missile defences. They also say it faces an impossible task, likened to "hitting a bullet with a bullet".
The US Missile Defence Agency said last month the system being built would be able to defend all 50 states against a limited ballistic missile attack by the end of 2004.