In a fresh challenge to Ukraine and its Western partners, Russian President Vladimir Putin on Saturday announced that Russia would station tactical nuclear weapons in neighbouring Belarus.?

Balarus is one of the closest Russian allies. The country also served as a staging ground of the Russian invasion of Ukraine in February 2022. Initially, one of the Russian attacking forces entered Ukraine from Belarus.

Stationing nuclear weapons in Belarus would mean that Russian weapons would be next door to three North Atlantic Treaty Organization (NATO) countries as Belarus shares borders with the NATO countries of Latvia, Lithuania, and Poland.

Putin's announcement comes at a time when the West has stepped up its support to Ukraine. Poland and fellow NATO member Slovakia have announced they would send MiG-29 fighter jets to Ukraine and United Kingdom announced earlier this to provide Ukraine with armour-piercing rounds containing depleted uranium.

Here we explain what are tactical nuclear weapons, what Putin said about nuclear weapons, and how West would respond to a Russian nuclear attack.

What did Putin say?

Russian President Vladimir Putin said that Russian placement of nuclear weapons in Belarus is perfectly fine and compliant to international norms.

Putin also compared the stationing of Russian nuclear weapons in Belarus to US deployment of weapons in military bases in ally countries.?

However, the immediate reason cited by Putin for stationing nuclear weapons in Belarus was the UK's decision this week to provide Ukraine with armour-piercing rounds containing depleted uranium. He falsely claimed that the rounds have nuclear components.

Putin argued that by deploying its tactical nuclear weapons in Belarus, Russia was following the lead of the United States, noting that the US weapons are based in Belgium, Germany, Greece, Italy, the Netherlands, and Turkey.

He said, "We are doing what they have been doing for decades, stationing them in certain allied countries, preparing the launch platforms and training their crews. We are going to do the same thing."

Putin said Belarusian President Alexander Lukashenko has long asked for the nuclear weapons as a counter to NATO. He noted that Russia helped modernise Belarusian military aircraft last year to make them capable of carrying nuclear warheads. He said 10 such planes were ready to go. He said nuclear weapons also could be launched by the Iskander short-range missiles that Russia provided to Belarus last year.?

What are tactical nuclear weapons?

Nuclear weapons, just like other weapons, can be categorised into two types — strategic and tactical.

Strategic weapons refer to weapons that have bigger objectives, such as destroying cities or larger targets with larger war-waging objectives in mind. Tactical weapons, on the other hand, are limited in their scope and the intention behind their usage is limited to arriving at a particular battlefied outcome.

For example, an example of a tactical nuclear weapon would be its use to stop adversary's progress in a particular theatre. On the contrary, strategic nuclear weapons would likely be used to bring the enemy to its knees entirely with a massive strike like the United States did in World War II when its nuclear weapons forced Japanese surrender.

This would mean that the two types would have different yields —or power— as they would produce vastly different results. Therefore, strategic and tactical nuclear weapons are classified such as per their intent, yield, and range.

More formally, tactical nuclear weapons are called "non-strategic nuclear weapons".

"Tactical (non-strategic) nuclear weapons (TNWs) typically refer to short-range weapons, including land-based missiles with a range of less than 500 km (about 300 miles) and air- and sea-launched weapons with a range of less than 600 km (about 400 miles)...In some respects, TNWs are more dangerous than strategic weapons. Their small size, vulnerability to theft, and perceived usability make the existence of TNWs in national arsenals a risk to global security," notes the think tank Nuclear Threat Initiative (NTI).

Though tactical nuclear weapons have lower yields as compared to strategic bombs, they still have many times yields than the bombs used on Japan in World War II by the United States, notes Air Commodore (Retired) Rippon Gupta in an article for the United Services Institution of India (USI).

He notes, "The yield of TNW [tactical nuclear weapons] is generally lower than that of strategic nuclear weapons, but larger ones are still very powerful and some warheads serve both roles. Modern tactical nuclear warheads have yields up to tens of kilotons or potentially hundreds; several times that of the weapons used in the atomic bombings of Hiroshima and Nagasaki. In TNW, it is difficult to combine sufficient yield and portability. Small, two-man portable, or truck-portable, tactical weapons (Special Atomic Demolition Munition)have been developed, for demolishing 'choke-points', such as tunnels and narrow mountain passes."

Russia is expected to have around 2,000 tactical nuclear weapons, as per an US estimate, reported Reuters.?

Reuters reported that Russia stores delivery platforms such as missiles and warheads —the actual weapons— separately. India also follows a similar practice for its nuclear weapons, though India has not publicised the strategic or tactical nature of its arsenal. Once Putin gives the order to launch the weapon, the delivery platform —like a missile— and the warhead will 'mated' and then launched. Besides missile, gravity bombs dropped from air or torpedoes can also be used to deliver tactical nuclear bombs.?

How the West would respond to Russian nuclear use?

The West is taking the threats issued by Russians and Putin very seriously on the issue of nuclear weapons.?

Last year, Putin once said that it has "all options" on the table in the Ukraine War. It was understood at the time that he was hinting at nuclear weapons.

US President Joe Biden has said you would start Armageddon if you use a nuclear weapon — whether strategic or tactical. The Armageddon refers to the final battle between the Good and Evil mentioned in Christian texts and is often used to refer to the conflict that would destroy Earth.

"I don’t think there is any such a thing as the ability to easily use a tactical nuclear weapon and not end up with Armageddon. [Putin is] not joking when he talks about the use of tactical nuclear weapons," said Biden, referring to the kind of weapons —tactical nuclear weapons— Putin might use.?

Ukrainian President Volodymyr Zelensky has said that NATO should not wait for Russia to strike and should employ "pre-emptive action".?

Pre-emptive actions "are needed so that [the Russians] know what awaits them if they use nuclear weapons. Not the other way around, waiting for Russia's nuclear strikes and then saying, 'Oh, you've done that, then get this'," said Zelensky, as per Washington Examiner.?

The West might respond to any nuclear attack with a tit-for-tat attack, short of attacking Russian mainland.?

"What you're trying to do is control the escalation, so if they hit you, you are going to have to respond — and you want to respond in such a way that prevents their further response. If you respond too weakly, well, have you really deterred them from responding? Or have you encouraged them? You make it very specific," said arms control export Joe Cirincione to Examiner, adding such a response would target, for example, the actual air base in Russia from which the strike originated.?

He added, "So you're not targeting Putin. You're not targeting Moscow. You’re going after the people who launched a strike. It’s a very specific escalation."

There is another line of thought that the West would go ahead with harder sanctions instead of nuclear strike in response. But this is likely to be ineffective as sanctions so far have not stopped Russia from waging a war.?

There are experts who say that even though these weapons are tactical, they have a very real risk of escalating the nuclear exchange to strategic level.

"Use of tactical nuclear weapons against similarly-armed opponents carries a significant danger of quickly escalating the conflict beyond anticipated boundaries, from the tactical to the strategic. The existence and deployment of small, low-yield tactical nuclear warheads could be a dangerous encouragement to forward-basing and pre-emptive nuclear warfare," notes Gupta in an article for USI, also cited above.