BRUSSELS -- NATO sees no sign that Russia has changed its nuclear posture, the head of the military alliance said Thursday, after President Alexander Lukashenko claimed that Belarus has already received some tactical nuclear weapons from Moscow.

In an interview on state television on Tuesday, Lukashenko brashly warned that he wouldn't hesitate to order their use if Belarus faced an act of aggression. Russian President Vladimir Putin has said the weapons will be deployed to Belarus next month and will remain under Moscow's exclusive control.

"We are, of course, closely monitoring what Russia is doing. So far, we haven't seen any changes in the nuclear posture that requires any changes in our posture," Stoltenberg told reporters before chairing a meeting of NATO defence ministers at the alliance's headquarters in Brussels.

NATO's secretive nuclear defence planning group is set to meet on Friday. The meeting has long been planned and is not a reaction to recent developments, but the alliance is concerned about Putin's threats and his decisions to pull Russia out of important arms limitation treaties.

"Russia's nuclear rhetoric and messaging is reckless and dangerous," Stoltenberg said. "Russia must know that a nuclear war cannot be won and must never be fought." He noted that "Russia has invested heavily in new modern nuclear capabilities and also deployed more nuclear capabilities, including close to NATO borders, for instance, in the high north."

Earlier this year, Putin announced the planned deployment of short-range nuclear weapons to Moscow's neighbour and ally Belarus in a move widely seen as a warning to the West as it stepped up military support for Ukraine. Russia is also using Belarus as a staging base for attacks in Ukraine.

During a meeting with Lukashenko on Friday, Putin said work on building facilities for the weapons would be completed by July 7-8, and they would be moved to Belarusian territory quickly after that.

U.S. President Joe Biden and his NATO counterparts are gathering for a summit on July 11-12 in the Lithuanian capital, Vilnius, about 35 kilometres (22 miles) from the Belarus border.