Russia's military is now stronger that any possible foe, Vladimir Putin has said.
The Russian president told an annual end-of-year meeting with the defence ministry: "We can say with certainty: we are stronger now than any potential aggressor."
Tensions between Russia and the West escalated after Russia's annexation in Crimea in 2014 and its involvement in the conflict in eastern Ukraine.
Last year, Russia began an air force operation in Syria to support president Bashar Assad, which irked the US in particular.
Both Russia and Nato members conducted a flurry of military drills near the Russian border this year. Russia has insisted that it is bolstering its forces at the border in reaction to a growing Nato threat.
Speaking at the defence ministry's headquarters in Moscow, Mr Putin said Russia should follow closely any military movement along its border as well as changes "in the military and political situation globally".
He said Russia should be swift in "adjusting plans to neutralise potential threats to our country."
Mr Putin made the comments after defence minister Sergei Shoygu presented his annual report, lauding Russia's military achievements in Syria as well as successful efforts to modernise the Russian army.
Among other things, Mr Shoygu said Russia "for the first time in its history" has fully covered the Russian border with early warning anti-missile systems. Shoygu also announced plans to send more troops to Russia's west, south-west and the Arctic region.
Mr Putin thanked the ministry for its work but added that "the situation might change very quickly" in case "we let ourselves relax even for a moment".