Russian Foreign Minister Sergei Lavrov accused NATO on Tuesday of deploying a significant amount of military hardware near Russia's borders and said Moscow could respond to security threats from Western countries and Ukraine if necessary.
US, NATO and Ukrainian officials have raised the alarm in recent weeks over what they say are unusual Russian troop movements near the border with Ukraine, and have suggested that Moscow might be preparing to launch an attack. Moscow has denied any plans to do so.
Lavrov said Ukrainian military manoeuvres and use of drones in the country's east, held by pro-Russian separatists, posed a threat to Russia, and it was ready to respond if needed.
"We simply cannot rule out the possibility that Kyiv will set out on a military adventure," he told a news conference in Moscow.
"President Putin stressed that we do not need conflict but if the West cannot hold back Ukraine - and on the contrary encourages it - of course we will take all the necessary steps to ensure our security."
Responding to concerns about its troop build-up, Russia has repeatedly said it is free to move its troops on its own territory and that such movements should not be a cause for alarm.