Russia has successfully tested a nuclear-capable, nuclear-powered underwater drone, President Vladimir Putin said on Wednesday, defying US President Donald Trump's warnings with Moscow's second test of a new nuclear weapons system in just a few days. Putin on Sunday oversaw a test of another advanced nuclear-capable weapon " the Burevestnik cruise missile, which he said had an "unlimited range". Trump called that exercise not "appropriate". "Yesterday, another test was conducted for another prospective system " the unmanned underwater device Poseidon', also equipped with a nuclear power unit," Putin said in televised remarks while visiting a military hospital treating Russian soldiers wounded in Ukraine.