If Russia uses weapons of mass destruction in Ukraine, NATO will respond in kind, according to President Joe Biden.
Biden said that they would respond if Putin used it.
The president spoke after a marathon of summit meetings with the European Union, G-7 partners and NATO allies.
Biden said he would support an effort to expel Russia from the G-20 group of economies.
The president refused to say if the United States has evidence that China helped Russia evade sanctions or sold American high tech equipment to Russia in violation of export bans.
Biden thinks that China understands that its economic futures are tied to the West more than it is to Russia.
NATO and the EU need to set up a system to review sanctions violations and when and how Russia can buy banned products, according to Biden.
To be sure that after a month, we will sustain what we are doing, not just next month, the following month, was the reason that Biden asked for the NATO meeting. That is what will stop Putin.
NATO Secretary-General Jens Stoltenberg told reporters that using chemical weapons would change the nature of the conflict in Ukraine.
It will be a blatant violation of international law and with far-reaching consequences if NATO uses such weapons.
NATO will soon provide Ukraine with equipment to protect against chemical, biological, radiological, and nuclear weapons, said NATO Secretary General Jens Stoltenberg. He wouldn't say what kind of support the alliance would provide in order to protect security.
Russia has used chemical weapons on the battlefield, including against Sergei Skripal and his daughter in London.
Frustrated with his slow progress in Ukraine, Putin has been signaling the possibility of using chemical or biological weapons to wipe out entire cities and force the country to surrender.
Biden warned earlier this week that Putin was trying to justify his own attack on Ukraine by accusing the U.S. of using biological or chemical weapons.
Russia has a long track record of accusing others of what they are either already doing or about to do, and that is the kind of projection that we have seen in the last couple of weeks. Biden said in an interview that it was very scary.
Biden said after the NATO meeting that the U.S. allies had accomplished all of his goals.
To support Ukraine with military and humanitarian assistance. In order to cripple Putin's economy and punish him for his actions, the second was to impose the most significant economic sanctions regime ever. Biden said that fortifying the eastern flank of our NATO allies was the third thing.