"There is a current moratorium (on nuclear tests) in effect," the Kremlin official pointed out.
"In his statement, President Trump mentioned that other countries are purportedly involved in testing nuclear weapons. Until now, we were unaware that anyone was engaged in the testing," he added, TASS reported.
Earlier, the US leader stated that he had instructed the Pentagon to immediately resume nuclear arms tests. Trump did not explain which tests precisely he had in mind and whether they involved the detonation of nuclear warheads.