Nato has accused Russia of stoking tensions in Europe with the deployment of anti-ship missiles to its westernmost Baltic region.
The alliance said Moscow's decision to send Bastion missile launchers to Kaliningrad, which borders Nato members Poland and Lithuania, was "aggressive military posturing".
The move would do nothing to "lower tensions or restore predictability to our relations", it told the Associated Press.
The statement came shortly after US State Department spokesman John Kirby called Russia's plans to permanently deploy its S-400 air missile defence system and ballistic Iskander missiles to Kaliningrad "destabilising to European security".
Dmitry Peskov, a Kremlin spokesman, hit back at Kirby's comments yesterday, calling Nato an "aggressive" military alliance.
"Russia does what it has to do. It has every sovereign right to take necessary measures throughout the territory of the Russian Federation," he said.
On Tuesday, Viktor Ozerov, chairman of the defence committee in Russia's Federation Council, said Moscow's deployment of Iskander missiles was a response to the US missile shield in eastern Europe.
The US activated the first phase of its land-based missile defence system in Romania in May. Another stage is due to be activated in Poland in 2018.
Russia has long been opposed to the missile shield, which it calls a danger to its national security. Nato says the shield guards against attack by "rogue" states such as North Korea.
Russia also criticised a report that claimed Russian tankers had smuggled jet fuel to Syria through European Union waters in contravention of European sanctions.
At least two Russian-flagged ships made deliveries, reported Reuters.
Russia's Defence Ministry said its tankers had been taking the fuel to its forces in Syria and that EU sanctions did not "concern" Moscow.
Tensions were also mounting yesterday between Russia and Ukraine after Moscow accused the Ukrainian security service of abducting two of its soldiers near the border between Russian-annexed Crimea and Ukraine. Kiev said the men had served in the Ukrainian army before deserting to Russia. But Sergei Lavrov, Russia's Foreign Minister, called their capture "an unlawful act of provocation ... towards Russian citizens on Russian soil."