Chemical weapons expert Hamish De Bretton-Gordon told Express.co.uk that Putin is “vulnerable” because his entire attention is focused on the invasion of Ukraine. The former army officer, who is currently training Ukrainians on how to survive chemical weapons, claims Putin’s forces are “bogged down” so far and is urging the UK Government and NATO allies to increase pressure on the Russian leader.

He stated that implementing a no-fly zone would allow the West to “get on the front foot” against Russia, adding that “if [Putin] f***s up in Ukraine, his entire deck of cards could fall down.”

This comes as Putin’s invasion of Ukraine appears to be moving more slowly than expected.

His forces, who appear to have suffered a high number of casualties, have yet to take Kyiv.

Since the invasion began on February 24, the US military has estimated that between 5,000 and 6,000 Russian soldiers have been killed.

However, Ukrainian armed forces claim that the figure is higher than 13,500.

According to US estimates, between 2,000 and 4,000 Ukrainian soldiers have been killed.

While NATO allies have imposed harsh sanctions on Russia and continue to supply Ukraine with weapons, they have so far refused to implement a no-fly zone.

Mr De Bretton-Gordon told Express.co.uk about the possibility of military intervention by the alliance: “We could engage Russian jets from far outside Ukraine’s airspace.

“Because you have so many assets that can do the same job from outside Ukraine airspace, you could actually have a no-fly zone without having British or American aircraft over Ukraine.

“I think we ought to look at that much more deeply.

“At the moment, Putin is entirely focused on Ukraine.

“We need to take his eye off. We need to give him other problems to think about.

“Militarily, he is 99 percent committed to Ukraine and he must know that.