The White House is finalizing plans to escalate the Russia-Ukraine war by easing restrictions on how Ukraine can use U.S. long-range missiles to hit targets deep inside Russian territory, according to reports.

When asked if the administration would lift restrictions on the use of long-range weapons, Biden told reporters Tuesday: “We’re working that out now.”

Russian President Vladimir Putin has already reacted to the White House’s plans, stating that such actions would represent the biggest escalation since the war began and signify that Russia is at war with NATO.

Politico report: The details of the plan are still coming together. But officials in Washington, London and Kyiv have in recent days discussed expanding the area inside Russia that Ukraine can hit with American and British-made weapons.

They’ve also discussed how to prevent additional cross-border attacks by Russia, including the U.S. agreeing to allow Ukraine to use U.K. long-range missiles that contain American parts to strike inside Russia.

The current conversations between Washington and Kyiv mark a significant change in tenor from the ones the two countries held earlier this summer. And it signals the Biden administration may be ready to finally agree to Kyiv’s requests to enable Ukraine’s military to more forcefully defend itself and to make more aggressive moves inside Russia.

The National Security Council declined to comment.

In an interview with PBS Newshour in June, national security adviser Jake Sullivan indicated that the U.S. might be willing to expand the area it would allow Ukraine to use U.S. weapons in Russia.

“It is not about geography. It is about common sense,” he said.

“If Russia is attacking or about to attack from its territory into Ukraine it only makes sense to allow Ukraine to hit back.”

For months, top U.S. officials have resisted calls by Kyiv and other European countries to lift all restrictions on the use of donated American weapons inside Russia.

In May, the Biden administration decided to let Ukraine use certain weapons to hit inside Russia, but prevented Kyiv from using long-range missiles.

Washington’s reasoning for keeping the remaining restrictions in place has oscillated between not wanting to escalate tensions with Moscow to arguing that Russia had moved too many of its high-value targets out of range for Ukraine to hit them even if permission were granted.