President Joe Biden has authorized Ukraine to use long-range ATACMS missiles inside Russia, something Biden had specifically prohibited until now, two U.S. officials confirmed to ABC News on Sunday.

The use of the ATACMS (Army Tactical Missile System) missiles, which have a range of 190 miles, inside Russia means that Ukraine could begin using them in Kursk, where 50,000 Russian troops, including 10,000 North Koreans, are attempting to recapture what Ukraine seized a few months ago.

In his nightly address to the nation, Ukrainian President Volodymyr Zelenskyy addressed the news that restrictions on the longer-range rockets had been lifted, saying, "Blows are not inflicted with words. Such things are not announced. The rockets will speak for themselves."

The U.S. had previously provided Ukraine with shorter-range ATACM missiles equipped with cluster munitions that could be used only on Ukrainian territory seized by Russia. But Ukraine has been lobbying for a long time to allow the use of the longer-range ATACMS to strike deep into Russia.

U.S. officials have publicly pushed back on how effective that system would be and pointed out that the U.S. does not have those missiles in large numbers. Instead, U.S. officials have spoken about how effective Ukraine's long-range drones have been in striking deep into Russia as a much cheaper alternative and in larger numbers. And the Biden administration had worried about crossing a red line with Russia, which has warned against allowing Ukraine to use longer-range weapons.

This is a developing story. Please check back for updates.