Washington (AFP) – US President Donald Trump said Thursday he had ordered the Pentagon to start nuclear weapons testing "on an equal basis" to China and Russia -- an announcement made just minutes before he held a high-stakes summit with Chinese leader Xi Jinping.
The move came after Russian President Vladimir Putin said on Wednesday that Moscow had successfully tested a nuclear-capable, nuclear-powered underwater drone, in defiance of Washington's warnings.
"Because of other countries testing programs, I have instructed the Department of War to start testing our Nuclear Weapons on an equal basis," Trump wrote in a social media post.
Following that announcement, Kremlin spokesman Dmitry Peskov told reporters on Thursday that the weapon tests announced by Putin did not constitute a direct test of an atomic weapon.
Both countries observe a de facto moratorium on testing nuclear warheads, though Russia regularly runs military drills involving systems that are capable of carrying such weapons.
The United States has been a signatory since 1996 to the Comprehensive Nuclear-Test-Ban Treaty, which bans all atomic test explosions, whether for military or civilian purposes.
It was not immediately clear whether Trump was referring to testing nuclear warheads, which the United States last did in 1992, or testing weapons systems capable of carrying atomic warheads.
Trump also claimed that the United States has more nuclear weapons than any other country, praising his own efforts to do "a complete update and renovation of existing weapons."
"Russia is second, and China is a distant third, but will be even within five years," he said.
The Stockholm International Peace Research Institute (SIPRI) said in its latest annual report that Russia possesses 5,489 nuclear warheads, compared to 5,177 for the United States and 600 for China.
In total, SIPRI estimates that the nine nuclear-armed countries -- Russia, the United States, China, France, the United Kingdom, Pakistan, India, Israel, and North Korea -- possess more than 12,200 warheads.
Trump told reporters aboard Air Force One that it had been "many years" since the United States had conducted nuclear tests.
"We don't do testing... we've halted it years, many years ago," he said, adding that it was "appropriate" to start again because others are testing.
"I'd like to see denuclearization... denuclearization would be a tremendous thing," he said.
He claimed "it's something we are actually talking to Russia about, and China would be added to that if we do something."
Trump kept the location and dates for testing vague during the news conference, but said earlier it would "begin immediately."
The Republican president was in South Korea to meet with Xi, with the leaders of the world's top two economies coming face-to-face for the first time in Trump's second term.
Chinese foreign ministry spokesman Guo Jiakun later urged the United States to "earnestly abide" by a global nuclear testing ban "and take concrete actions to safeguard the global nuclear disarmament."
The United States conducted 1,054 nuclear tests between July 16, 1945, when the first test was conducted in New Mexico, and 1992, as well as two nuclear attacks on Japan during World War II.
It is the only country to have used nuclear weapons in combat.
The last US nuclear test explosion was in September 1992, with a 20-kiloton underground detonation at the Nevada Nuclear Security Site.
Then-president George H.W. Bush imposed a moratorium on further tests in October 1992 that has been continued by successive administrations.
Nuclear testing was replaced by non-nuclear and subcritical experiments using advanced computer simulations.
Putin announced on Wednesday the successful testing of a nuclear-capable, nuclear-powered underwater drone, the second weapons test in days after that of the Burevestnik cruise missile.
In televised remarks broadcast from a military hospital treating Russian soldiers wounded in Ukraine, Putin said there was "no way to intercept" the torpedo drone dubbed "Poseidon."
"Regarding the tests of Poseidon and Burevestnik, we hope that the information was conveyed correctly to President Trump," Kremlin spokesman Peskov told journalists, including AFP, during a daily briefing on Thursday.
"This cannot in any way be interpreted as a nuclear test."
He implied that Russia would also test nuclear warheads if Trump ordered a live test of an atomic weapon.
"If someone departs from the moratorium, Russia will act accordingly," Peskov said.