Russia and Belarus have commenced the second stage of tactical nuclear weapons drills, as part of Moscow's efforts to deter the West from increasing support for Ukraine.

Russia announced these exercises last month, following statements that it would not rule out deploying troops to Ukraine under certain conditions.

The United States and some other NATO allies have stated that Kyiv is permitted to use Western-supplied weapons.

The exercises, which took place last month, focused on preparing for nuclear missions and how to arm and deploy missiles.

In the drills that began on Tuesday, the Russian Ministry of Defence stated that Russian and Belarusian troops would undergo joint training in non-strategic nuclear weapons used in combat.

The exercises aim to maintain the readiness of personnel and equipment to ensure the 'sovereignty and territorial integrity' of the alliance between Russia and Belarus.

Speaking to reporters, Kremlin spokesman Dmitry Peskov said the situation in Europe was 'quite tense' and that such drills and maintaining combat readiness were important in view of the 'hostile decisions and actions' by the US and its allies and their 'daily provocations.

' Since sending thousands of troops into Ukraine, Russian President Vladimir Putin has repeatedly warned that Russia could use nuclear weapons to defend itself in extreme situations.

Last year, Russia moved some of its tactical nuclear weapons into Belarus, which also borders Ukraine and NATO members Poland, Latvia, and Lithuania.

Belarus's President Alexander Lukashenko has relied on close ties with Russia and provided his country as a staging ground for the war in Ukraine.

Tactical nuclear weapons include air bombs, warheads for short-range missiles, and artillery munitions, and are meant for use on a battlefield.

Usually, they are less powerful than strategic weapons—huge warheads that arm intercontinental ballistic missiles and are intended to destroy entire cities.

Russian President Vladimir Putin has noted, however, that even Russia's battlefield nuclear weapons are much more powerful than the two atomic bombs the US dropped on Japan in August 1945.

Last week, Putin declared that the West was wrong to assume that Russia would never use its atomic arsenal.

The country's nuclear doctrine envisages the use of nuclear weapons in case of a threat to 'the very existence' of the Russian state.

Officials in the US have said they have seen no change to Russia's strategic posture, although senior intelligence officials say they have to take Moscow's remarks about nuclear weapons seriously.

Russia and the United States are by far the world's biggest nuclear powers, holding about 88 percent of the world's nuclear weapons, according to the Federation of American Scientists.