Russia will move its tactical nuclear weapons close to the western borders of Belarus, the Russian envoy to Minsk said Sunday, placing them at NATO's threshold in a move likely to further escalate Moscow's standoff with the West.

In one of Russia's most pronounced nuclear signals since the beginning of its invasion of Ukraine 13 months ago, President Vladimir Putin said on March 26 that Russia will station tactical nuclear weapons in Belarus.

The two Slavic neighbors are formally part of a "union state" and have been in talks for years to integrate further, a process that has accelerated after Minsk allowed Moscow to use Belarusian territory to send troops into Ukraine last year.