Russia has taken the presidency of the UN Security Council despite Ukraine urging members to block the move, reports said.
On Friday, the Kremlin said it planned to “exercise all its rights” in the role, according to The Guardian.
The US has urged Russia to “conduct itself professionally” when it assumes the role, saying there is no means to block Moscow from the post, The Guardian report said.
The role is mostly procedural, but Moscow's ambassador to the UN, Vasily Nebenzia, told the Russian Tass news agency that he planned to oversee several debates, including one on arms control, BBC reported.
He said he would discuss a "new world order" that, he said, was coming to "replace the unipolar one".
The last time Russia had the presidency, February 2022, it launched a full-scale invasion of Ukraine. Each of the council's 15 members takes up the presidency for a month, on a rotating pattern.
It means the Security Council is being led by a country whose president is subject to an international arrest warrant for alleged war crimes, according to the BBC.
The International Criminal Court - which is not a UN institution - issued the warrant for Vladimir Putin last month.
Despite Ukraine's complaints, the United States said it could not block Russia - a permanent council member - from assuming the presidency, the BBC report said.
The other permanent members of the council are the UK, US, France, and China.
Ukrainian Foreign Minister Dmytro Kuleba called Russia's presidency "the worst joke ever for April Fool's Day" and a "stark reminder that something is wrong with the way international security architecture is functioning".
The BBC quoted Ukraine's presidential adviser, Mykhaylo Podolyak as saying the move was "another rape of international law... an entity that wages an aggressive war, violates the norms of humanitarian and criminal law, destroys the UN Charter, neglects nuclear safety, can't head the world's key security body".