President Vladimir Putin on Friday said Russia could amend its military doctrine by introducing the possibility of a pre-emptive strike to disarm an enemy, in an apparent reference to a nuclear attack.

He spoke in response to a question from a reporter who asked him to clarify his statement from earlier this week on the use of nuclear weapons.

Speaking to reporters just days after warning that the risk of nuclear war was rising but Russia would not strike first, Putin said Moscow was considering whether to adopt what he called Washington's concept of a pre-emptive strike.

"First of all, the United States has the concept of a pre-emptive strike. Second, it is developing a disarming strike system," Putin told reporters in Kyrgyzstan.

Putin said Moscow might need to think about adopting US "ideas for ensuring their own security."

"We're just thinking about it," he said.

"If a potential adversary believes that it is possible to use the concept of a pre-emptive strike, but we do not, then nevertheless this makes us think about the threats that such ideas pose to us."

Putin claimed that Russia's cruise missiles and hypersonic systems were "more modern and even more efficient" than those in the United States.

On Wednesday, Putin warned that nuclear tensions were rising, although he insisted that Moscow would not be the first to deploy atomic weapons.

At the same he said: "If we aren't the first to use them under any circumstances, then we will not be the second to use them either."

The same day the US State Department rebuked the Russian leader, saying "any loose talk of nuclear weapons is absolutely irresponsible."

Banished from public consciousness for decades, the nightmare of nuclear warfare has surged back to prominence since Putin sent troops into Ukraine in February, highlighting the erosion of the Cold War global security architecture.

With Moscow on the back foot in its offensive, the military stalemate has raised fears that Russia could resort to its nuclear arsenal to achieve a military breakthrough.