Valery Gerasimov, head of Russia's General Staff, "noted a strengthening of NATO's frontline military presence close to Russia's borders", while meeting the commander of NATO forces in Europe Curtis Scaparrotti.

Gerasimov added that "this doesn't help reduce tensions" between Moscow and the alliance, said a defence ministry statement after they met in Baku, Azerbaijan.

NATO and the US have accused Russia of violating a Cold War arms control treaty (known as the INF) with ground-launched missiles with a range of 500 kilometres ( to 5,500 kilometres, which Moscow denies.

The US last week warned it would withdraw from the treaty signed in 1987 within 60 days if Russia does not dismantle missiles that the US claims breach the deal.

Russian President Vladimir Putin has warned such a move would only push Moscow to develop nuclear missiles banned by the treaty.

NATO held massive exercises close to Russia's borders in October and November after Russia held major military exercises on NATO's eastern flank in 2017.

Russian Foreign Minister Sergei Lavrov this month blasted "the recklessness of NATO".

US-Russia ties are under deep strain over accusations Moscow meddled in the 2016 US presidential election.