Russia go station tactical nuclear weapons for Belarus, President Vladimir Putin don tok.
President Putin say di move no go violate nuclear non-proliferation agreements and compare am to di US stationing im weapons for Europe, according to Russian state media.
Moscow no go transfer control of im arms to Minsk, e add join.
Di US say e no believe say Russia dey prepare to use di nuclear weapons after di announcement.
"We never see any reason to adjust our own strategic nuclear posture," di US Defense Department tok inside one statement.
"We remain committed to di collective defence of di Nato alliance."
Belarus share a long border with Ukraine, and with Nato members Poland, Lithuania and Latvia.
Dis go be di first time since di mid-1990s wey Moscow go based nuclear arms outside di kontri.
Di Soviet Union collapse for 1991 mean weapons become based for four newly-independent states - Russia, Ukraine, Belarus and Kazakhstan - with di transfer of all warheads to Russia completed for 1996.
Di Belarusian regime na firm Kremlin ally and supporter of di invasion of Ukraine.
President Putin tell Russian state television on Saturday say Belarusian leader Alexander Lukashenko don long raise di issue of stationing tactical nuclear weapons for Belarus.
"Nothing dey unusual here either," e tok. "Firstly, di United States don dey do dis for decades. Dem don for long deploy dia tactical nuclear weapons on for di territory of dia allied countries."
Russia go start to dey train crews to operate di weapons from next week. Di construction of a storage facility for tactical nuclear weapons for Belarus go dey completed by 1 July, President Putin add.
A small number of Iskander tactical missile systems, wey dey used to launch nuclear weapons, already don dey transferred to Belarus, President Putin tok.
E no specify wen dem go send weapons demselves.
Di announcement to station weapons for Belarus come only days after Chinese President Xi Jinping visit to Moscow, during which Russia and China issue a joint statement saying "all nuclear powers must not deploy their nuclear weapons beyond their national territories, and dem must withdraw all nuclear weapons wey dey deployed abroad."
On Sunday, a top security adviser to Ukrainian President Volodymyr Zelensky tok say Russia plans na "step towards internal destabilisation" of Belarus and predict anti-Russian sentiment for di kontri go grow. "Di Kremlin take Belarus as a nuclear hostage," Oleksiy Danilov write for Twitter.
President Putin comments come after President Zelensky renewed his plea for more military support from his Western allies.
Earlier dis week, some 18 kontri signe one agreement to supply di war-torn kontri with at least one million artillery shells over di next year.
But for one interview with a Japanese newspaper, President Zelensky say Ukraine no fit launch a potential counter-offensive for di east of di kontri until further ammunition arriv.