Biden: Russia chemical attack is 'real threat'

WASHINGTON

: United States President Joe Biden has left the

White House

for a four-day trip to Europe, where he will meet with key allies to discuss Russia's invasion of Ukraine. As he departed Wednesday, Biden told reporters the possibility that

Russia

could use chemical weapons in the Ukraine war is a "real threat".

He said he would say more on the subject directly to the leaders he was meeting with Thursday.

There are fears that Russia could use chemical or nuclear weapons as its invasion stalls amid logistical problems and fierce Ukrainian resistance.

Biden's first stop is Brussels, where he'll attend a hastily arranged emergency Nato summit. He will also participate in meetings of the European Union and the Group of Seven, which includes the world's richest democracies.

He'll travel to Warsaw on Friday to meet Polish officials.