Questions were raised on Thursday about the possibility of Russia using tactical nuclear weapons in the Ukraine war, after the US Central Intelligence Agency warned that Moscow could resort to such a move that would be an unprecedented development since 1945.

The hypothesis was previously floated shortly after the conflict began, when Russian President Vladimir Putin indicated that he had ordered his military commanders to put Russia's "nuclear deterrent force on alert".

On Thursday, CIA Director William Burns renewed the warning that Russia's military setbacks in Ukraine could prompt Putin to use a tactical or low-yield nuclear weapon.

Speaking in Atlanta, Burns said despair would push Putin and the Russian leadership, given the military setbacks they have faced so far, to take such a step.

But he acknowledged that the United States had not seen much "empirical evidence" of actual deployments of such weapons that would exacerbate Western concerns.

U.S. intelligence suggests Russia is likely to use tactical nuclear weapons after heavy losses in Ukraine (Reuters)

Russia possesses many tactical nuclear weapons, which are less powerful than the bomb the United States dropped on Hiroshima during World War II, and can be equipped with a carrier with a range of less than 5500,<> kilometers.

At the end of March, Matthew Polegg, an analyst at Britain's Chatham House think tank, said: "At the vertical level there is a real danger; they desperately need military victories to invest them politically."

"A chemical weapon would not change the shape of war, but a tactical nuclear weapon would destroy a Ukrainian city. "It's unlikely, but it's not impossible, and if it does, it would torpedo the hypothesis of a 70-year-old nuclear deterrent."

Russia's military doctrine is controversial. Many experts and military officials, especially in Washington, assert that Moscow has abandoned the Soviet doctrine of not initiating the use of nuclear weapons.

Russia's military doctrine is characterized by a principle called "escalation in order to contain escalation," which could involve a first-strike with a low-yield nuclear weapon to force NATO to back down.

Ready nuclear warheads

Recent Russian positions have not dispelled doubts surrounding this interpretation.

In a statement to CNN, Kremlin spokesman Dmitry Peskov said Russia would not use nuclear weapons in the context of war with Ukraine unless it faced an "existential threat," citing one of Russia's official dogmatic foundations, without giving any explanation.

According to the Journal of Atomic Scientists, "Russia has deployed 1588,812 nuclear warheads," including 576 warheads equipped with ground-based missiles, 200 warheads equipped with submarines, and <> warheads equipped with bombers.

Experts agree that Moscow may use a tactical nuclear weapon during the ongoing war for deterrence (Getty Images)

According to Pavel Luzin, an analyst at the Moscow-based Riedel think tank, Russia could use a tactical nuclear weapon "to demoralize an adversary and to prevent the enemy from continuing to fight."

Luzin said the goal was primarily to wave the weapon for deterrence, "but if the opponent wants to continue fighting, it can be used more explicitly."

But even if the threats achieve their objective, the risk cannot be completely ruled out.

A senior French official, speaking on condition of anonymity, said: "In the event of evasion or humiliation, a vertical escalation is envisaged. This is part of Russia's strategic culture of moving forward with intimidation and escalation with the aim of containing the escalation."

"Putin did not enter this war to lose it."

Exclude

But others insist that nuclear weapons are impossible, arguing that if Putin decides to annihilate even a Ukrainian village to show how determined he is, all human life in the region could be wiped out for decades.

"The political price will be enormous; he will lose the little support left for him; the Indians will retreat and so will the Chinese," said William Alberk, an analyst at the International Institute, adding: "I don't think Putin will do that."

But Russia would not have enjoyed its current military status without nuclear weapons; it would not pose such a serious threat to its conventional forces, which, despite demonstrating enormous destructive capacity in Ukraine, suffer from real tactical, operational, and logistical weaknesses.

A Western diplomat said that after the Russian invasion of Ukraine, "there are no more borders" that cannot be crossed, but he hoped there would be no use of nuclear force, the last use of which in the war dates back to August 1945, <>, when Nagasaki became the second Japanese city to be bombed with atomic bombs after Hiroshima.