WASHINGTON -- In a major shift of his administration's policy on the Ukraine crisis, US President Joe Biden has authorized Kyiv to use US-supplied long-range missiles to strike targets inside Russia, US media reported Sunday.

The greenlight would allow the Ukrainian troop's first use of Western-made ATACMS missiles, reported US media outlets including The Associated Press, The New York Times and The Washington Post, citing two anonymous US officials.

The White House or the Pentagon has not yet confirmed the decision.

The Biden administration has allowed Kyiv to use HIMARS, a US-developed light multiple rocket launcher with a range of about 50 miles (80.5 km), for cross-border attacks in Russia to defend the eastern Ukrainian city of Kharkiv and the surrounding region since May, when Russian forces began an offensive there.

The administration, however, had ruled out permitting Ukraine to use the longer-range ATACMS inside Russia, fearing a drastic escalation of the conflict. The ATACMS has a range of about 190 miles (305.8 km).

US officials said they do not expect the shift of the policy to "fundamentally change the course" of the conflict, The New York Times reported, adding that Biden could authorize Kyiv to use the weapons elsewhere outside Kursk.