President Vladimir Putin has described the development of Nato's US-led missile defence programme as a threat to global security and vowed that Russia will take the necessary steps to maintain a strategic parity.
Mr Putin, speaking at a meeting with military officials, scoffed at US claims that the shield is not aimed against Russia but instead intended to fend off a missile threat from Iran.
The system includes a site in Romania that became operational on Thursday and a site in northern Poland where US and Polish officials broke ground on Friday for a facility due to be ready in 2018.
"Just a few years ago, our partners in the West, in Europe and the United States, were all speaking in one voice, telling us that they need a missile defence system to protect from missile and nuclear threats from Iran," Mr Putin said, adding that such a threat has ceased to exist after last year's nuclear deal between Iran and world powers.
"The threat is gone, but the creation of the missile defence system is continuing."
Mr Putin said Russia "will do everything needed to ensure and preserve the strategic balance, which is the most reliable guarantee from large-scale military conflicts", but will not get drawn into an arms race.
Earlier this week, Colonel General Sergei Karakayev, chief of the Russian military's Strategic Missile Forces, said new types of Russian intercontinental ballistic missiles accelerate faster and are equipped with manoeuvrable warheads, making them more difficult to intercept.
In another potential response, the military has talked about stationing its state-of-the art Iskander missiles to Russia's westernmost Baltic outpost of Kaliningrad, which borders Nato members Poland and Lithuania.
Last year, the missiles were airlifted there during military manoeuvres in a demonstration of their swift deployment capability, but were pulled back to their permanent base after the drills.
The Iskander missiles, which have a range of up to 300 miles, would put most of Poland in reach if deployed from the Kaliningrad region.
Dmitry Rogozin, a deputy prime minister in charge of military industries, said after the meeting with MrPutin that Russia will use technologies that would allow it to "neutralise any threat with minimal resources." He did not elaborate.
Russia has long described the US-led missile shield as a top security challenge. Russian military officials have said while the current system does not pose a threat to Russia's massive nuclear missile force, it could erode the nation's nuclear deterrent when it grows more powerful in the future.
"They aren't defensive systems, they are part of the US strategic nuclear potential deployed on the periphery, in eastern Europe," MrPutin said.
"Now, after the deployment of those missile defence elements, we will have to think about how we can fend off the threats to the Russian Federation's security."