"US-South Korean military exercises that began on March 7, although formally routine, are in reality unprecedented in their scope, the number and types of weapons involved, as well as the type of maneuvers being carried out," the ministry noted.
It said the developments in and around the Korean Peninsula "are causing growing concern."
"Russia has repeatedly publicly expressed its opposition to such manifestation of military and political pressure on Pyongyang," Moscow added.
Military drills between South Korea and the United States, believed to be the two countries' largest ever joint exercises amid increased tensions on the Korean Peninsula, kicked off earlier in the day.
Key Resolve and Foal Eagle, two joint US-South Korean military exercises on dispatching the US overseas forces to the Korean Peninsula, presuppose practicing the elimination of Pyongyang's weapons of mass destruction.
As many as 15,000 US servicemen joined around 290,000 South Korean soldiers in the drills expected to last until April 30. In 2015, the United States sent one-quarter of the current troop numbers, while the number of South Korean soldiers is now 1.5 times higher.