TOKYO: United Nations Secretary-General Antonio Guterres on Monday urged countries with nuclear weapons to stick to their no-first-use commitment to their atomic arsenals, warning that the nuclear arms race has returned amid growing international tension.

'This is the moment...to ask the nuclear-armed countries to commit to the principle of non-first-use and to commit to not use and not threaten the non-nuclear countries,' Guterres said at a news conference in Japan's capital Tokyo, two days after he visited the city of Hiroshima to commemorate the victims of the Aug. 6, 1945, atomic bombing.