The announcement by Russian President Vladimir Putin that he intends to deploy tactical nuclear weapons on the territory of Belarus appears to be another attempt to raise the stakes in the conflict in Ukraine.

It follows Putin’s warnings that Moscow is ready to use “all available means,” to fend off attacks on Russian territory, a reference to its nuclear arsenal.

A look at Putin’s statement and its implications:

HOW DID PUTIN EXPLAIN HIS MOVE?

Putin said President Alexander Lukashenko of Belarus has long urged Moscow to station its nuclear weapons in his country, which has close military ties with Russia and was a staging ground for the invasion of neighboring Ukraine on Feb. 24, 2022.

Russia already has helped modernize Belarusian warplanes to make them capable of carrying nuclear weapons — something that Belarus’ authoritarian leader has repeatedly mentioned.

In remarks broadcast Saturday, Putin said the immediate trigger for the deployment of Russia’s tactical nuclear weapons to Belarus was Britain’s decision to provide Ukraine with armor-piercing shells containing depleted uranium. Putin toned down his language after first falsely claiming that such rounds have nuclear components, but he insisted they pose an additional danger to the civilian population and could contaminate the environment.

Putin also said that by stationing tactical nuclear weapons in Belarus, Russia will be doing what the United States has done for decades by putting its nuclear weapons in Belgium, Germany, Italy, the Netherlands and Turkey. He alleged the Russian move doesn’t violate an international treaty banning the proliferation of nuclear weapons, even though Moscow has argued before that the U.S. has breached the pact by deploying them on the territory of its NATO allies.

Putin’s move contrasted with a statement he and Chinese President Xi Jinping issued after their talks in the Kremlin last week, which spoke against nuclear powers deploying atomic weapons outside their territories, in an apparent jab at the United States.

WHAT ARE TACTICAL NUCLEAR WEAPONS?

Tactical nuclear weapons are intended to destroy enemy troops and weapons on the battlefield. They have a relatively short range and a much lower yield than nuclear warheads fitted to long-range strategic missiles that are capable of obliterating whole cities.

Unlike the strategic weapons, which have been subject to arms control agreements between Moscow and Washington, the tactical weapons never have been limited by any such pacts, and Russia hasn’t released their numbers or any other specifics related to them.

The U.S. government believes Russia has about 2,000 tactical nuclear weapons, which include bombs that can be carried by aircraft, warheads for short-range missiles and artillery rounds.

While strategic nuclear weapons are fitted to land- or submarine-based intercontinental ballistic missiles that are constantly ready for launch, tactical nuclear weapons are stored at a few tightly guarded storage facilities in Russia, and it takes time to deliver them to combat units.

Some Russian hawks long have urged the Kremlin to send a warning to the West by moving some tactical nuclear weapons closer to the aircraft and missiles intended to deliver them.

WHAT EXACTLY WILL RUSSIA DO?

Putin said Russia already has helped upgrade 10 Belarusian aircraft to allow them to carry nuclear weapons and their crews will start training to use them from April 3. He noted Russia also has given Belarus the Iskander short-range missile systems that can be fitted with conventional or nuclear warheads.

He said the construction of storage facilities for nuclear weapons in Belarus will be completed by July 1. He didn’t say how many nuclear weapons will be stationed there or when they will be deployed.

Putin emphasized that Russia will retain control over any nuclear weapons deployed to Belarus, just like the U.S. controls its tactical nuclear weapons on the territory of its NATO allies.

If Moscow sends nuclear weapons to Belarus, it will mark their first deployment outside Russian borders since the early 1990s. Belarus, Ukraine and Kazakhstan inherited massive nuclear arsenals after the collapse of the Soviet Union in 1991 but agreed to ship them to Russia in the following years.

WHAT ARE THE POSSIBLE CONSEQUENCES BEHIND PUTIN’S MOVE?

With his latest statement, Putin again is dangling the nuclear threat to signal Moscow’s readiness to escalate the war in Ukraine.

The deployment of tactical nuclear weapons to Belarus, which has a 1,084-kilometer (673-mile) border with Ukraine, would allow Russian aircraft and missiles to reach potential targets there more easily and quickly if Moscow decides to use them. It would also extend Russia’s capability to target several NATO members in Eastern and Central Europe.

The move comes as Kyiv is poised for a counteroffensive to reclaim territory occupied by Russia.

Dmitry Medvedev, deputy head of Russia’s Security Council, warned last week that attempts by Ukraine to reclaim control over Crimea was a threat to “the very existence of the Russian state,” something that warrants a nuclear response under the country’s security doctrine. Russia illegally annexed Crimea from Ukraine in 2014.

“Every day of supplying Western weapons to Ukraine makes the nuclear apocalypse closer,” Medvedev said.

Ukrainian military analyst Oleh Zhdanov said Putin’s goal is to discourage Ukraine’s Western allies from providing Kyiv with more weapons ahead of any counteroffensive.

Putin is “using nuclear blackmail in a bid to influence the situation on the battlefield and force Western partners to reduce supplies of weapons and equipment under the threat of nuclear escalation,” Zhdanov said. “The Belarusian nuclear balcony will be looming over not only Ukraine, but Europe as well, creating a constant threat, raising tensions and rattling the nerves of Ukrainians and their Western partners.”

WHAT ARE UKRAINE AND THE WEST SAYING?

Ukraine has responded to Putin’s move by calling for an emergency meeting of the U.N. Security Council. A U.N. spokesman referred questions on the issue to the Security Council, which had announced no meeting on it by Monday afternoon.

“The world must be united against someone who endangers the future of human civilization,” the Ukrainian Foreign Ministry said.

White House National Security Council spokesman John Kirby said Monday that U.S. officials “haven’t seen any movement of any tactical nuclear weapons or anything of that kind” since Putin’s announcement on Belarus. He has said Washington has seen nothing to prompt a change in its strategic deterrent posture.

NATO rejects Putin’s claim that Russia only is doing what the U.S. has done for decades, saying the Western allies act with full respect of their international commitments.

“Russia’s nuclear rhetoric is dangerous and irresponsible,” NATO spokesperson Oana Lungescu said, adding that the alliance hasn’t yet seen any change in Russia’s nuclear posture.

Lithuania, which borders Belarus, described Putin’s statement as “yet another attempt by two unpredictable dictatorial regimes to threaten their neighbors and the entire European continent,” calling them “desperate moves by Putin and Lukashenko to create another wave of tension and destabilization in Europe.”

Russia’s Foreign Ministry responded to Western criticism by pointing out Washington and its allies had ignored repeated Russian calls for the withdrawal of U.S. nuclear weapons from Europe. The ministry reaffirmed Moscow’s right to take “the necessary additional steps to ensure security of Russia and its allies.”

Aamer Madhani in Washington and Yuras Karmanau in Tallinn, Estonia contributed to this report.