Belarus on Tuesday launched drills involving missiles and warplanes capable of carrying tactical nuclear weapons, which close ally Russia has deployed there amid tensions with the West over Ukraine.

The Belarusian maneuvers began a day after Russia announced plans to hold similar drills simulating the use of battlefield nuclear weapons in what it cast as a response to statements by Western officials signaling possibly deeper involvement in the war in Ukraine. It was the first time such an exercise had been publicly announced by Moscow.

Belarus’ Defense Minister Viktor Khrenin said a unit of Iskander short-range missiles and a squadron of Su-25 fighter jets will take part in the drills.

The maneuvers began as Russian President Vladimir Putin was inaugurated to a fifth term on Tuesday, vowing to ensure Russia’s security.

Last year, Russia moved some of its tactical nuclear weapons into Belarus, which also borders Ukraine and NATO members Poland, Latvia and Lithuania. Belarus’ authoritarian President Alexander Lukashenko has relied on close ties with Russia and provided his country as a staging ground for the war in Ukraine.