Russia’s military on Tuesday began drills involving tactical nuclear weapons that were announced by Russian authorities earlier this month in an apparent warning to senior Western officials who had spoken about the possibility of deeper involvement in the war in Ukraine.

It was the first time Russia has publicly announced drills involving tactical nuclear weapons, although its strategic nuclear forces regularly hold exercises.

According to a statement by the Defense Ministry released Tuesday, the first stage of the new drills envisioned “practical training in the preparation and use of non-strategic nuclear weapons,” including nuclear-capable Kinzhal and Iskander missiles.

The maneuvers are taking place in the Southern Military District, which consists of Russian regions in the south, including on the border with Ukraine; Crimea, illegally annexed from Ukraine in 2014; and four Ukrainian regions that Russia illegally annexed in 2022 and partially occupies.