A senior Russian official said on Tuesday that NATO’s reinforcement of its borders with Russia was no longer a figure of speech and Moscow should be prepared for possible aggressive action, Russia’s TASS news agency reported.

The agency was quoting Dmitry Medvedev, deputy chairman of Russia’s Security Council.

Medvedev, an ally of Russian President Vladimir Putin, warned NATO last week that if Sweden and Finland joined the U.S.-led military alliance then Russia would deploy nuclear weapons and hypersonic missiles in a European exclave.

Russia says carried out dozens of strikes in eastern Ukraine