(RIA Novosti) – Western officials have reacted with alarm at Russia’s deployment of tactical missiles on areas bordering NATO members states, describing it as a potentially destabilizing move.

Russian officials have confirmed that missiles capable of carrying nuclear warheads have been moved to the Western Military District – a territory that abuts all three Baltic States and Poland – in a measure that marks an escalation in Moscow’s campaign to dissuade a US-backed missile shield program in Central Europe.

US State Department spokeswoman Marie Harf said at a briefing on Monday that Washington “urged Moscow to take no steps to destabilize the region.”

Russian’s Defense Ministry has defended the deployment, saying that it violated no international agreements. Russia has not revealed the number and exact location of the missiles, and it remains unclear how long they have been in the region.

The 4-ton mobile Iskander-M missiles in question are designed to carry nuclear warheads and have a range of 400 kilometer (250 miles) and fly in a quasi-ballistic trajectory to confuse missile defense systems.

The Associated Press cited US General Philip Breedlove, the head NATO commander in Europe, as saying Tuesday that such a move would demonstrate the need for improved communication between Russia and NATO.

On Tuesday, Latvia’s Foreign Ministry said in a statement that it was “alarmed at Russia’s steps and considers [its] actions unjustified.”

Mindaugas Zickus, a foreign policy advisor to the Lithuanian President, told a local radio station on Tuesday that the missile deployment illustrated duplicity on Russia’s part.

“Russia’s declared support for closer dialogue and strategic cooperation with the European Union and NATO is incompatible with such actions,” Zickus said.

In 2011, then-president Dmitry Medvedev announced a set of measures that Russia would employ to counter a proposed US-led missile defense system in Europe that included the construction of radar systems for air defense and stationing nuclear-equipped Iskander missiles in the region.

The United States insists the missile shield is aimed at defending its allies from emerging-threat states Iran and North Korea.

Analysts consider high-speed, short-range nuclear missiles destabilizing as they drastically shorten the time between a missile launch and nuclear detonation increasing the risk of a preemptive strike.

Russian defense officials said last week that the recently struck deal with Iran to abandon its nuclear weapons ambitions negates the need for the missile shield plans. The US Defense Secretary said on Monday that missile defense system would go forward as planned and was not connected to the Iran deal.