Joe Biden said Nato will “respond in kind” if Vladimir Putin uses chemical weapons in Ukraine.
Speaking after a Nato meeting in Brussels on Thursday, the US president added: “The nature of the response would depend on the nature of the use”.
Mr Biden said Nato was “more united” than it had ever been as the alliance agreed to double its defences by moving 40,000 troops to its eastern flank in light of the Russian invasion.
He said Mr Putin had underestimated the “cohesion” of western countries.
Earlier today, Jens Stoltenberg, Nato’s secretary general, confirmed four new battlegroups will be sent to Slovakia, Hungary, Bulgaria and Romania – in addition to four others in the Baltic countries and Poland.
He also pledged military aid, including additional weapons. It comes after Ukrainian president Volodymyr Zelensky, via video link, asked for “1 per cent” of Western allies’ weapons.
Following the meeting, Nato leaders announced they had also agreed to supply hazmat suits to Ukrainians amid growing concerns Russian president Vladimir Putin may use chemical and biological weapons.
