Lukashenko says Belarus has started receiving Russian nuclear weapons.

Belarus President Aleksandr G. Lukashenko said on Tuesday that the country is beginning to receive nuclear weapons from Russia, a long-threatened provocation and the latest sign of the deteriorating relationship between Russia and the West.

“We have missiles and bombs that we received from Russia. A bomb three times more powerful than Hiroshima and Nagasaki,” Mr Lukashenko said in Russian in an interview with Russian state television.

Mr. Lukashenko’s claim could not be independently verified. For months, he and President Vladimir V. Putin of Russia, a close ally, have spoken publicly about plans to move tactical nuclear weapons — short-range weapons designed for use in combat — to Belarus. That would bring such weapons closer to the war in Ukraine, but also closer to NATO members such as Poland.

The US government estimates that Russia has about 2,000 tactical weapons, which have lower explosive power than strategic weapons designed to destroy entire cities far from the battlefield.

There was no immediate response from the White House to Mr. Lukashenko’s claim. On Monday, National Security Council spokesman John Kirby said the Biden administration had seen no evidence of changes in Russia’s nuclear commitment that would force the United States to change its stance on nuclear weapons. He said Mr Lukashenko’s “constant rhetoric” is “consistent with reckless and irresponsible ways of talking about nuclear capabilities”.

Mr Lukashenko’s statement that the weapons had already arrived seemed to contradict Mr Putin’s remarks when the two leaders met in Sochi, Russia, last week.

At the time, Mr Putin said Russia would begin deploying tactical nuclear weapons in Belarus immediately after storage facilities were readied on July 7 and 8, according to a Kremlin translation of the conversation between the two leaders.

Mr Putin has raised the prospect of resorting to nuclear weapons several times since ordering a full-scale invasion of Ukraine last year. US officials have repeatedly condemned Mr Putin’s comments as dangerous saber-rattling, but they have also said the risk of nuclear escalation remains low.

In March, Putin said he could plant nuclear weapons in Belarus by summer, a claim analysts say was likely a gaffe to pressure the West to end its support for Ukraine. Mr Putin said Moscow would retain control over weapons placed in Belarus.