Russia's defense minister says the military has strengthened its forces in southwestern Russia with long-range weapons to fend off emerging new threats.

Sergei Shoigu said Friday the move has been taken in response to "attempts by some nations to expand their military presence near our borders," an apparent reference to NATO.

Shoigu said that troops of the Southern Military District have been beefed up with "precision long-range weapons" and air defense. He added that the Russian navy potential in the region has increased by one-third.

Amid Russia-West tensions over the Ukrainian crisis, the U.S. has sent additional military equipment to the Baltics and Central Europe. Last week, a U.S. missile defense site also became operational in Romania. Russia has threatened to take retaliatory steps to maintain a strategic parity.