President Biden on Friday stressed that the U.S. and NATO allies would not fight Russia in Ukraine, describing such a scenario as "World War III."

"We’re going to continue to stand together with our allies in Europe and send an unmistakable message. We will defend every single inch of NATO territory with the full might of the united and galvanized NATO," Biden said after announcing additional sanctions on Russia. "We will not fight a war against Russia in Ukraine. Direct conflict between NATO and Russia is World War III, something we must strive to prevent."

The president's comments were his starkest warning yet as some experts and journalists have asked what type of Russian escalation might trigger a U.S. military response.

Some lawmakers have pushed for establishing a no-fly zone over Ukraine, something White House officials have ruled out because it would involve U.S. and allied forces potentially shooting down Russian planes in Ukrainian airspace.

And multiple reporters have asked in recent days whether the use of chemical weapons by Russia would trigger a U.S. military response.

But Biden and his team have been consistent that they have no intention of sending American forces into Ukraine to fight Russia, warning that doing so would likely lead to a protracted and potentially global war with another nuclear power.

"The President and our NATO partners have not changed their assessment about their plans to send U.S. troops in," White House press secretary Jen Psaki said Thursday after warning Russia could be setting up a pretext for a chemical weapons attack.

Biden said Friday Russia would pay a "severe price" if it carries out a chemical weapons attack.

(THE HILL)