Moscow may change the timing for use of its nuclear weapons if threats against Russia increase, the RIA state news agency cited Andrei Kartapolov, the head of the Russian lower house’s defence committee, as saying on Sunday.

The former general’s comments follow recent warnings by President Vladimir Putin that Moscow may change its nuclear doctrine, which lays out the conditions in which such weapons could be used.

“If we see that the challenges and threats increase, it means that we can correct something in (the doctrine) regarding the timing of the use of nuclear weapons and the decision to make this use,” the agency quoted Kartapolov as saying.

“But of course, it’s too early to talk about specifics now.”

Russia’s 2020 nuclear doctrine sets out when its president would consider using a nuclear weapon: broadly as a response to an attack using nuclear or other weapons of mass destruction, or conventional weapons “when the very existence of the state is put under threat”.

Putin has also said Russia could test a nuclear weapon, if necessary, though he saw no need to do so at the present time.

The heightened rhetoric on nuclear weapons comes as both Russian and U.S. diplomats say that Russia’s war in Ukraine, launched against its smaller neighbour in 2022, is in the most dangerous phase yet.