Russian President Vladimir Putin on Wednesday announced plans to broaden Russia's rules on the use of its nuclear weaponry, allowing it to unleash a nuclear response in the event of a "massive" air attack.

The proposals would also permit Moscow to respond with nuclear weapons against non-nuclear states if they are supported by nuclear powers -- a clear reference to Ukraine and its Western backers.

Kremlin spokesman Dmitry Peskov said the planned changes "must be considered a specific signal".

"A signal that warns these countries of the consequences if they participate in an attack on our country by various means, not necessarily nuclear," Peskov told reporters.

Without mentioning Ukraine by name, Peskov said Russia's "nuclear deterrence is being adjusted on account of elements of tension that are developing along the perimeter of our borders".

He also said there was "no question" of Russia boosting its nuclear arsenal.

Moscow residents on Thursday told AFP they were worried by the announcement.

"Using the threat of nuclear weapons is always bad. We don't need another Cuban missile crisis," said Dimitri, a 21-year-old student who declined to give his surname.

Vadim, a 43-year-old artist who also only gave his first name, said: "An escalation is underway, of course, it is alarming."

For others, like 60-year-old pensioner Vladimir, the new doctrine could be beneficial and "bring pretentious Europeans to reason".

The move "can reinforce security and force people in Ukraine and the United States to think", said Igor Diakov, also a retiree in Moscow.

"Europe will tremble because all the red lines have been crossed and they think they cannot be punished for it. But we won't let them get away with it."

Tatiana Nikiforova, a 49-year-old Russian teacher, deferred to her country's leadership.

"We must have faith in our leaders, there is no other way," she said.

The proposed changes to Russia's nuclear doctrine, which Putin himself has the power to approve, come as Ukraine is seeking permission from Western allies to use long-range precision weaponry to strike targets deep inside Russia -- so far to no avail.

Kyiv says it is necessary to target Russia's airfields and military infrastructure that it uses to launch attacks on Ukraine, though the White House is cautious about enabling further escalation.

The West has accused Putin of irresponsible nuclear sabre-rattling throughout the Ukraine conflict, with the Kremlin leader having issued multiple apparent threats about Moscow's willingness to deploy its nuclear weapons.