WARSAW, Poland (AP) — Poland’s President Andrzej Duda said Tuesday that Russia already is in the process of shifting some short-range nuclear weapons to neighboring Belarus, a move that Duda said will shift the security architecture of the region and the entire NATO military alliance.

Both Russian President Vladimir Putin and his Belarusian counterpart Alexander Lukashenko said last month that Moscow already had shipped some of its tactical nuclear weapons to Belarus after announcing the plan in March. The U.S. and NATO haven’t confirmed the move.

NATO Secretary-General Jens Stoltenberg denounced Moscow’s rhetoric as “dangerous and reckless,” but said in July that the alliance hadn’t seen any change in Russia’s nuclear posture.

Tactical nuclear weapons are intended for use on the battlefield and have a short range and a low yield compared with much more powerful nuclear warheads fitted to long-range missiles. Russia said it would maintain control over those it sends to Belarus.

Duda made his comments at a joint news conference with visiting Portuguese President Marcelo Rebelo de Sousa.

“I was telling President (Sousa) about the implementation of the declarations by Vladimir Putin that Russia’s tactical nuclear weapons will be moved to the territory of Belarus,” Duda said. “Indeed, this process is taking place, we are seeing that.”

Duda gave no details, but said that in an “obvious way it is changing the architecture of security in our part of Europe. It is changing the architecture of security in our immediate neighbourhood, but also of the eastern flank of NATO, at the same time. So in fact it is changing the situation for all of the alliance.”

Lukashenko says that hosting Russian nuclear weapons in his country is meant to deter aggression by NATO member Poland, even though Warsaw has made no such threats. Poland is offering neighbour Ukraine military, humanitarian and political backing in its struggle against Russia’s invasion and is taking part in international sanctions on Russia and Belarus.

De Sousa pledged continuing support for Ukraine’s struggle and for other countries in the region, saying it is as important to Portugal as the situation in its own neighbourhood.

“We are united, we stand in solidarity, without any hesitations and I have dully taken note of the Polish concerns over what may be understood as the need to be closely watching any moves that may question the eastern borders of the European Union or of NATO,” de Sousa said.