Russian President Vladimir Putin has just lowered the bar for use of nuclear weapons in his war with Ukraine, suggesting he did this after Biden allowed Ukraine to fire missiles into parts of the Russian state.

Here’s more from NBC News:

Russian President Vladimir Putin formally lowered the threshold for his country’s use of nuclear weapons Tuesday, days after the United States allowed Ukraine to strike inside Russia using American missiles.

The Kremlin announced that Putin had approved an updated nuclear doctrine — a document that governs how Russia uses its nuclear arsenal — including the declaration that Moscow could unleash a nuclear strike if subject to an attack by a nonnuclear country that has the support of a nuclear state.

The changes to Russia’s nuclear doctrine mark the most significant saber-rattling yet by the Kremlin, which has consistently warned about possible nuclear war throughout the now 1,000 days since its full-scale invasion of Ukraine.

“The nuclear doctrine update was required to bring the document in line with the current political situation,” Kremlin spokesman Dmitry Peskov told the TASS state news agency in comments published early Tuesday.

Peskov outlined Moscow’s new threat in light of Washington’s shift in policy: that the use of Western nonnuclear missiles by Ukraine’s military against Russia under the new doctrine could lead to a nuclear response.

Still, the use of nuclear weapons would be a “last resort measure,” he added.

Joe Biden’s administration has responded to this by saying they aren’t surprised:

This war could very easily escalate into something far worse before Trump even gets in office. But even if it doesn’t, you can be sure he will be blamed for any escalation after he’s president which happens because of this.