Questions were raised again 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 a development unprecedented since 1945.

The hypothesis was previously put forward 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".

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

Burns said - in a speech in Atlanta - that "desperation would push Putin and the Russian leadership - given the military setbacks they are facing so far" - to take such a step.

But he acknowledged that the United States had not seen much "practical evidence" of actual deployments of these weapons that would exacerbate Western concerns in this regard.

US intelligence suggests that Russia will use tactical nuclear weapons after the heavy losses it incurred in Ukraine (Reuters)

Russia has many tactical nuclear weapons, which are less powerful than the bomb dropped by the United States on Hiroshima during World War II, and can be equipped with a carrier with a range of less than 5,500 km.

At the end of last March, an analyst at the British think-tank Chatham House, Matthew Poleg, said that "on the vertical level there is a real danger; they urgently need to achieve military victories to invest politically."

"Chemical weapons will not change the shape of war, but a tactical nuclear weapon would destroy a Ukrainian city. It is unlikely, but not impossible, and if it happened, it would undermine the 70-year-old premise of nuclear deterrence," he added.

The Russian military doctrine is the subject of controversy.

Many experts and military officials - especially in Washington - assert that Moscow has abandoned the Soviet doctrine that it should not take the initiative to use nuclear weapons.

Russian military doctrine is characterized by a principle called "escalation to contain escalation", which would include a first strike with a low-yield nuclear weapon to force NATO to back down.

nuclear warheads ready

The recent Russian positions did not dispel the doubts surrounding this interpretation.

In a statement to CNN, Kremlin spokesman Dmitry Peskov said that Russia would not use nuclear weapons in the context of war with Ukraine unless it faced an "existential threat", referring to one of the foundations of the Russian official doctrine, without give any clarification.

Technically, Russia is equipped;

According to the "Journal of Atomic Scientists", "Russia has deployed 1,588 nuclear warheads," including 812 warheads that were equipped with land-based missiles, 576 warheads that were equipped with submarines, and 200 warheads that were equipped with launchers.

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

According to Pavel Luzhin, an analyst at the Moscow-based Riedel Research Center, Russia could use a tactical nuclear weapon "to demoralize an opponent, and to prevent the enemy from continuing the fight."

Lusine said that the goal is primarily to brandish this weapon for deterrence purposes, "but if the opponent wants to continue fighting, it can be used more explicitly."

But even if the threats achieve their goal, the danger cannot be completely ruled out.

A high-ranking French official stated - on condition of anonymity - that "in the event of stagnation or humiliation, a vertical escalation can be envisaged. This is part of the Russian strategic culture, which stipulates moving forward with intimidation and escalation in order to reach a containment of escalation."

"Putin did not enter this war to lose it," he added.

exclusion

But others insist on the impossibility of using nuclear weapons, arguing that if Putin decided to annihilate even a Ukrainian village to show his determination, all human life in the region would be perished for decades.

"The political price will be huge; he will lose what little support he has left; the Indians will back down and so will the Chinese," said William Alberck, an analyst at the International Institute, adding, "I don't think Putin will do that."

But Russia would not have had its current military stature without nuclear weapons;

It would not have posed such a serious threat with its conventional forces, which - despite their display of enormous destructive power in Ukraine - suffer from real weaknesses at the level of tactics, operations and at the logistical level.

A Western diplomat said that after the Russian invasion of Ukraine "there are no longer any borders" that cannot be crossed, but he hoped not to resort to nuclear power, whose last use in the war dates back to August 9, 1945, when Nagasaki became the second Japanese city to be bombed. After Hiroshima.