Sergei Shoigu made the announcement at a meeting with top military officials. He pointed to a growing number of flights by US strategic bombers near Russia's borders, deployments of NATO warships and increasingly frequent and major drills by alliance forces.

He charged that such actions “destroy the international security system and force us to take the relevant countermeasures."

“We will form another 20 units and formations in the Western Military District until the year's end,” Shoigu said

He added the military units in Western Russia have commissioned about 2,000 new pieces of weaponry this year.

Asked Monday about Russia’s plans, NATO Secretary-General Jens Stoltenberg noted that “Russia over the last years has invested heavily in new, modern military capabilities, from conventional to nuclear weapon systems” and "has been willing to use military force against neighbors, in Georgia, in Ukraine”.

“This is one of the main reasons why NATO over the last years has increased the readiness of (its) armed forces,” he told reporters before Tuesday's meeting of the alliance's foreign and defence ministers.

Currently, thousands of NATO troops, several warships and dozens of aircraft are taking part in military exercises stretching across the Atlantic, through Europe and into the Black Sea region.

NATO says the war games aren't aimed at Russia, but the Steadfast Defender 21 exercises are simulating the 30-nation military organization’s response to an attack on any one of its members. It will test NATO’s ability to deploy troops from the U.S. and keep supply lines open.

Last month, a troop buildup in Russia’s south and southwest near the Ukrainian border raised concerns in Ukraine and the West, which urged Moscow to withdraw its forces.

Russia annexed Ukraine's Crimean Peninsula in 2014 following the ouster of the country's Moscow-friendly president and then threw its weight behind separatist rebels in eastern Ukraine. More than 14,000 people have been killed in seven years of fighting in eastern Ukraine.

Russia has recalled some troops from its western part after sweeping maneuvers in April, but Shoigu ordered them to leave their weapons behind for Russia's Zapad (West) 2021 military exercises in September.

He noted Monday that preparations for the exercises, which will be conducted jointly with Belarus, are now in their final stage and emphasized that the maneuvers have an “exclusively defensive character.”

Last week, Russia offered political support to its ally Belarus, which diverted a Ryanair plane flying from Greece to Lithuania as part of a ruse to arrest a dissident journalist. The European Union denounced the flight's diversion as piracy and responded by barring the Belarusian flag carrier from its airspace and advising European airlines to skirt Belarus' airspace.