Russian President Vladimir Putin on Wednesday ordered a snap check of the battle-readiness of the armed forces in the west and center of the country, including the area bordering Ukraine.
"The commander-in-chief has set the task of checking the capability of the armed forces to deal with crisis situations posing a threat to the military security of the country," said Defense Minister Sergei Shoigu, quoted by the Interfax news agency.
The drill involves army, navy and airforce troops based in the western military district, a vast territory bordering Ukraine, Belarus, the Baltic states, Finland and the Arctic.
The previously unannounced move comes amid turmoil in Ukraine that toppled pro-Russian president Viktor Yanukovych and unleashed separatist sentiment in some largely Russian-speaking regions such as Crimea.
Putin ordered a similar check last year, however, and said at the time that such drills should become regular events.
The drill, which Shoigu said is to check the troops' effectiveness in "resolving crisis situations threatening military security and also anti-terrorist (operations)," will run from Wednesday to March 3.
The last such check was carried out in July last year, involving more than 80,000 troops in far eastern Russia. It was the largest such snap check since the breakup of the Soviet Union in 1991.