Russian President Vladimir Putin announced plans on Saturday to station tactical nuclear weapons in neighboring Belarus, a warning to the West as it steps up military support for Ukraine.

Putin said he was responding to Britain’s decision this past week to provide Ukraine with armor-piercing rounds containing depleted uranium. Russia falsely claimed these rounds have nuclear components.

He said Russia would maintain control over the tactical nuclear weapons and the construction of storage facilities for them in Belarus would be completed by July 1.

Belarusian President Alexander Lukashenko has long asked for the weapons, Putin said, speaking in an interview on Russian state television.

Russia has used the territory of Belarus as a staging ground to send troops into Ukraine, and Moscow and Minsk have maintained close military ties.

Putin noted that Russia helped modernize Belarusian military aircraft last year to make them capable of carrying nuclear warheads. He said 10 such planes were ready to go. He said nuclear weapons also could be carried by the Iskander short-range missiles that Russia provided to Belarus last year.

Tactical nuclear weapons are intended for use on the battlefield, unlike more powerful, longer-range strategic nuclear weapons.