President Biden’s decision to allow Ukraine to fire U.S.-made and supplied missiles deeper into Russia — a major policy shift announced over the weekend after months of intense lobbying by Kyiv — has drawn a furious response from Moscow. While there was no immediate reaction directly from the man who launched the nearly three-year war on his neighboring nation, lawmakers aligned with President Vladimir Putin in Russia said Monday that the move was unacceptable and warned it could lead to a third world war.

Mr. Biden authorized Ukraine’s President Volodymyr Zelenskyy to use American-made missiles with a range of almost 200 miles, known as ATACMS, to strike deeper inside Russian territory than the Ukrainians have to date. 

So far, Ukraine’s attacks beyond the immediate border region inside Russia have been limited to non-U.S. — and much less potent—  weapons such as explosive drones. ATACMS are far more destructive and harder to shoot down as they head for their programmed targets.

Zelenskyy’s government had been pushing Washington for permission to use the missiles for long-range attacks for some time but the Biden administration had been reluctant given concerns about potentially escalating the war.

Over the weekend, however, the calculus apparently changed. The decision came almost 1,000 days into the full-scale war in Ukraine, and with Mr. Biden about two months away from handing over the White House keys to President-elect Trump, who’s seen as far less supportive of Ukraine’s ambitions of hanging onto all of its Russian-occupied territory.

It also came as Russia hit Ukraine with a devastating missile attack, highlighting Ukraine’s desperate desire for the ability to target Russian weapons systems deeper inside the country before they’re launched, which Zelenskyy has stressed for more than a year.

Many of the Russian rockets launched Sunday targeted energy infrastructure but a ballistic missile carrying cluster munitions also struck a residential part of the northern city of Sumy, killing 11 people, including two children, and leaving more than 80 others wounded. Fresh strikes hit apartment buildings in the southern city of Odesa on Monday, killing at least eight people including a child, regional authorities said.

Residents in Sumy were targeted as they slept, and Ukrainian officials called the Sunday missile and drone salvo one of the largest Russian attacks since the start of the war.

With the change in policy from the outgoing administration in Washington, Ukrainian forces will be able to retaliate harder, reaching further into Russia than ever before. Ukrainian forces have launched drone attacks into Russian territory, including targeting Moscow, for months, but with limited effect.

Zelenskyy welcomed the change in U.S. policy, saying “strikes are not made with words… The missiles will speak for themselves.” 

But Ukraine’s war-time leader also appeared to acknowledge the change in tack in Washington that Trump’s second swearing-in will bring, with a far greater emphasis expected on striking a negotiated truce than on defending Ukraine’s sovereign territory from unilateral annexation by Russia.

“It is certain that the war will end sooner with the policies of the team that will now lead the White House. This is their approach, their promise to their citizens,” Zelenskyy said in an interview with a Ukrainian news outlet, adding that Ukraine “must do everything so that this war ends next year, ends through diplomatic means.”

In Moscow, meanwhile, senior lawmaker Leonid Slutsky slammed Mr. Biden, accusing him of deciding “to end his presidential term and go down in history as ‘Bloody Joe’.”  

Senator Vladimir Dzhabarov, meanwhile, told Russia’s state-run Tass news agency that Biden’s decision represented “a very big step toward the beginning of the third world war.”

The official newspaper of the Russian state, Rossiyskaya Gazeta, warned “the madmen who are drawing NATO into a direct conflict with our country may soon be in great pain.”

Putin had personally warned against the eventuality previously, issuing a warning in September that U.S. permission for Ukraine to fire American-supplied long-range missiles at his country, “would mean that NATO countries, the United States, and European countries, are parties to the war in Ukraine.”

But Putin himself has dramatically raised the stakes in the war since then, by overseeing the deployment of at least 11,000 North Korean troops to fight alongside Russian forces. They’ve joined the battle in Russia’s western Kursk region, a significant portion of which Ukrainian troops occupied earlier this year in a surprise offensive.

The parameters of the permission granted to Ukraine for the use of the ATACMS haven’t been confirmed, but according to reports, they include — and may be limited to — Ukraine using the missiles to attack Russian defensive positions in Kursk.

James Nixey, who heads the Russia and Eurasia program at the London-based Chatham House think tank, said in an analysis Monday that the change in policy from Washington was “not a game changer,” especially if it included a limitation on where Ukraine can use the ATACMS.

“The relaxation of range limits for Ukraine’s usage of US ATACMS follows the overall pattern of America’s approach to this war: to make sure Ukraine cannot inflict significant damage on Russia… but to allow small increases in hardware provision and their usage over extended periods of time,” he said. “If it is true that the authorization for usage extends only to the Kursk region (and is therefore primarily directed at North Korean troops); then, again, this fits the pattern, and means the overall effects on the war will be negligible.”

Imtiaz Tyab

Imtiaz Tyab is a CBS News correspondent based in London and reports for all platforms, including the “CBS Evening News,” “CBS Mornings,” “CBS Sunday Morning” and CBS News 24/7. He has extensive experience reporting from major global flashpoints, including the Middle East and the war on terror.