Biden says the US and NATO 'would respond' if Putin uses chemical weapons in Ukraine

• Biden on Thursday warned Russia that the use of chemical weapons in Ukraine would trigger a US and NATO response.
• "We would respond if he uses it. The nature of the response would depend on the nature of the use," he said.

President Joe Biden on Thursday said that the US and NATO would respond if Russia uses chemical weapons in Ukraine, though did not expand on what the response would look like.

"We would respond if he uses it," Biden said during news conference at NATO headquarters in Brussels, after a reporter noted that the Biden administration has warned of the "real threat" of Russian President Vladimir Putin using chemical weapons and asked the president if this would trigger a military response from the US and NATO.

"The nature of the response would depend on the nature of the use," the president added. Biden declined to comment on whether the US had intelligence suggesting that Putin is deploying, moving, or considering the use of chemical weapons, but US officials have repeatedly warned that Russian forces may use chemical weapons.

When asked by another reporter to clarify whether the use of chemical weapons by Putin would trigger a military response by the US and NATO, Biden said, "It would trigger a response in kind."

Biden is in Europe this week to meet with allies to discuss the Ukraine war and will also visit US troops stationed in Poland on Friday.

Russia's unprovoked war in Ukraine turned a month old on Thursday. Since it began, the West has taken unprecedented steps to isolate Russia politically and economically.

NATO has also ramped up its military presence in Eastern Europe, while members of the alliance have increased the supply of military assistance to Ukraine — including lethal aid. The US, for its part, has sent Javelin anti-tank missiles, Stinger missiles, and weaponized drones, among other forms of aid.

Though they're willing to supply Ukraine with weapons, the US and NATO have remained firm that they are not interested in direct conflict with Russia. Ukraine is not a NATO member, and the alliance is not obligated to defend it. This is why NATO has rejected calls from Ukraine for a no-fly zone, as it would require the alliance to shoot down Russian warplanes and effectively amount to a declaration of war.

But drastic actions from Russia could potentially pull NATO, of which the US is a leading member, into the war despite its best efforts to avoid the direct involvement of alliance troops.

Russia has met stiffer resistance than it expected in Ukraine, and NATO estimates that the Russian military has already seen up to 40,000 battlefield casualties, a tally that of those injured and killed.

With Russia struggling to make progress on the ground in Ukraine, there are growing concerns that Putin could resort to extreme steps — including the use of weapons of mass destruction like chemical or nuclear weapons.

NATO Secretary General Jens Stoltenberg on Wednesday warned, "Any use of chemical weapons would fundamentally change the nature of the conflict. It will be a blatant violation of international law and it will have widespread and severe consequences."

Stoltenberg said that the use of chemical weapons would not just be a "catastrophe for the people of Ukraine," but risk the spread of chemical agents into NATO territory.

"I will not speculate beyond the fact that NATO is always ready to defend, to protect and to react to any type of attack on a NATO Allied country," Stoltenberg added.