President Vladimir Putin said he'd sought an "open dialogue" with the West.
Almost a year after Russian President Vladimir Putin launched a full-scale invasion of neighboring Ukraine, the two countries are engaged in a struggle for control of areas throughout the east and south.
Putin's forces pulled out of key positions in November, retreating from Kherson as Ukrainian troops led a counteroffensive targeting the southern port city. Russian drones have continued bombarding civilian targets throughout Ukraine, knocking out critical power infrastructure as winter sets in.
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Several explosions rocked Kyiv's Shevchenko District, a large area in the center of the capital that includes the historic old town as well as several government offices, Mayor Vitali Klitschko said on Monday.
"Several explosions in the Shevchenkiv District -- in the center of the capital," Klitschko said on Telegram. "All services follow in place. Details later."
-ABC News' Will Gretsky
At least 12 people were killed overnight in missile strikes on residential Zaporizhzhia neighborhoods, Ukrainian officials said on Sunday.
"Russia continues its missile terror against civilians in Zaporizhzhia," Dmytro Kuleba, Ukraine's foreign affairs minister, said.
Kuleba said there had been 12 Russian missile strikes on civilian areas overnight. Zaporizhzhia’s governor said at least 12 people had been killed in the attack and 87 were injured.
"We urgently need more modern air and missile defense systems to save innocent lives," he said.
Missiles destroyed about five homes, with another 40 damaged, Anatolii Kurtiev, secretary of the Zaporizhzhia city council, said on Telegram. He said missiles struck apartment high-rises.
The Parliament of Ukraine said 49 others were injured, including six children.
"There may still be people under the rubble. Rescue operation is underway," officials wrote on the Parliament of Ukraine's Twitter account. "Russia is unable to fight the Armed Forces of #Ukraine, so it resorts to what its 'military' does best -- attacking civilians and claiming they were 'military targets.'"
Russian President Vladimir Putin ordered a commission to investigate an explosion that damaged a key bridge linking Crimea and Russia. Russia had been using the bridge as a key supply route for bringing in troops and ammunition into southern Ukraine.
The Ukrainian Security Service declined to comment on rumors of its involvement in the bridge's explosion.
Putin also signed a decree instructing tighter security for the bridge and the infrastructure supplying electricity and natural gas to the peninsula.
The blast coincided with the naming of Air Force General Sergei Surovikin as the commander of all Russian troops in Ukraine.
-ABC News' Patrick Reevell and Jason Volack
Ukraine's Zaporizhzhya Nuclear Power Plane lost its last external power source due to renewed shelling, the International Atomic Energy Agency Director General Rafael Grossi said in a statement Saturday.
The plant is now relying on emergency diesel generators for the electricity it needs for reactor cooling and other essential nuclear safety and security functions, according to Grossi.
The plant's connection to the power line was cut at around 1 a.m. local time. Sixteen of the plant’s diesel generators started operating automatically, providing its six reactors with power. After the situation stabilized, 10 of the generators were switched off, according to Grossi.
"The resumption of shelling, hitting the plant’s sole source of external power, is tremendously irresponsible. The Zaporizhzhya Nuclear Power Plant must be protected," Director General Grossi said. "I will soon travel to the Russian Federation, and then return to Ukraine, to agree on a nuclear safety and security protection zone around the plant. This is an absolute and urgent imperative."
