KYIV, Ukraine (AP) — President Joe Biden’s decision to let Ukraine strike targets inside Russia with U.S.-supplied long-range missiles was met with ominous warnings from Moscow, a hint of menace from Kyiv and nods of approval from some Western allies.

Biden’s shift in policy added an uncertain and potentially crucial new factor to the war on the eve of its 1,000-day milestone.

News of Biden’s change came on the day a Russian ballistic missile with cluster munitions struck a residential area of Sumy, a city in northern Ukraine, killing 11 people, including two children, and injuring 84 others.

On Monday, another Russian missile attack started fires in two apartment blocks in Odesa, in southern Ukraine. At least eight people were killed and many more were injured, Ukrainian lawmaker Oleksii Honcharenko said in a video he posted on Telegram from the site of the attack.

Washington is easing limits on what Ukraine can strike with U.S.-made weaponry, U.S. officials told The Associated Press on Sunday, after months of ruling out such a move over fears of escalating the conflict and bringing about a direct confrontation between Russia and NATO.

The scope of the new firing guidelines isn’t clear. But the change came after the U.S., South Korea and NATO said recently that North Korean troops are in Russia and apparently are being deployed to help the Russian army drive Ukrainian troops out of Russia’s Kursk border region.

Russia is also slowly pushing Ukraine’s outnumbered army backward in the eastern Donetsk region. It has also conducted a devastating and deadly aerial campaign against civilian areas in Ukraine.

Kremlin spokesman Dmitry Peskov on Monday referred journalists to a statement made by Russian President Vladimir Putin in September, in which he said allowing Ukraine to target Russia would significantly raise the stakes in the conflict.

It would change “the very nature of the conflict dramatically,” Putin said at the time. “This will mean that NATO countries — the United States and European countries — are at war with Russia.”

Peskov claimed that Western countries supplying long-range weapons also provide targeting services to Kyiv. “This fundamentally changes the modality of their involvement in the conflict,” Peskov said.

Last June, Putin warned that Russia could provide long-range weapons to others to strike Western targets in response to NATO allies allowing Ukraine to use their arms to attack Russian territory. He also reaffirmed Moscow’s readiness to use nuclear weapons if it sees a threat to its sovereignty.

President-elect Donald Trump, who takes office in about two months’ time, has raised uncertainty about whether his administration would continue the United States’ vital military support for Ukraine. He has also vowed to quickly end the war.

Ukrainian President Volodymyr Zelenskyy gave a muted response to the approval that he and his government have been requesting of Biden for more than a year.

“Today, much is being said in the media about us receiving permission for the relevant actions,” Zelenskyy said in his nightly video address Sunday.

“But strikes are not made with words. Such things are not announced. The missiles will speak for themselves,” he said.

The foreign minister of NATO member Lithuania, Gabrielius Landsbergis, said he’s not “opening the champagne” yet as it remains unclear exactly what restrictions have been lifted and whether Ukraine has enough of the U.S. weapons to make a difference.

Margus Tsahkna, the foreign minister of Estonia which is another Baltic country that fears a military threat from Russia, said easing restrictions on Ukraine was “a good thing.”

“We have been saying that from the beginning — that no restrictions must be put on the military support,” he said at a meeting of senior European Union diplomats in Brussels. “And we need to understand that situation is more serious (than) it was even maybe like a couple of months ago.”

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Lorne Cook in Brussels contributed.

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Follow AP’s coverage of the war in Ukraine at https://apnews.com/hub/russia-ukraine