Russia-Ukraine updates: Putin suspends key US-Russia nuclear treaty in speech denouncing West

Russian President Vladimir Putin has signed laws finalizing the illegal annexation of four regions of neighboring Ukraine -- more than 15% of the country's territory -- even as his military struggles to maintain control over the newly absorbed areas.

The documents completing the annexation of Ukraine's Donetsk, Luhansk, Kherson and Zaporizhzhia regions -- in defiance of international laws -- were published on a Russian government website on Wednesday morning.

Earlier this week, the Russian parliament ratified treaties making the occupied areas part of Russia. The move followed what the Kremlin called referendums in the four Ukrainian regions, which the West rejected as a sham.

The annexed areas are not all under control of Russian forces, which are battling a massive counteoffensive effort by Ukrainian troops.

President Joe Biden and Vice President Kamala Harris spoke with Ukrainian President Volodymyr Zelenskyy on Tuesday, underscoring that the U.S. will never recognize areas annexed by President Vladimir Putin as Russian territory and offering additional security assistance.

Biden announced a $625 million security assistance package that includes additional weapons and equipment, according to a statement from the White House.

Biden also promised to impose "severe costs" on any individual, entity or country that "provides support to Russia’s purported annexation."

-ABC News' Justin Gomez

Since Russian President Vladimir Putin announced a national mobilization last month, more than 355,000 people have left the country, according to Russian independent media.

Roughly 200,000 people escaped to Kazakhstan, 80,000 left for Georgia and 65,000 departed for Finland. Some 6,000 people also fled to Mongolia and there are reports of people fleeing to Armenia, Kyrgyzstan, Uzbekistan and Tadjikistan.

Russian Defense Minister Sergei Shoigu said Tuesday that more than 200,000 people have been mobilized since Sept. 21.

-ABC News' Tanya Stukalova

Ukraine has made a major breakthrough in the country’s south that now threatens to collapse part of the Russian front line there, similar to Ukraine’s counteroffensive in the northeast last month.

Ukrainian forces have advanced over 18 miles in two days, driving deep behind Russia’s front line in the Kherson region and advancing south along the Dnipro river.

Russian journalists reported that Russian forces on Monday were forced to pull back from the village of Dudchany.
Multiple Russian military bloggers, who are often embedded with Russian troops, say that Ukrainian troops now heavily outnumber Russian troops there.

The advance, if it continues, has huge implications for the war. Russia’s position is increasingly in danger of collapsing, which would make it all but impossible to defend the city of Kherson, the capital of the region annexed by Russian President Vladimir Putin four days ago.

-ABC News' Patrick Reevell