Russia-Ukraine updates: 2 US veterans who joined Ukrainian forces missing

Russian Foreign Minister Sergei Lavrov said the West has declared a "total hybrid war" on Russia and warned that everyone will feel the consequences on Saturday.

"The collective West has declared a "total hybrid war" against us and it is hard to predict how long it will last, but it is clear that everyone, without exception, will feel the consequences," he said at a meeting of the Council for Foreign and Defense Policy on Saturday.

Lavrov added: "We did our best to avoid a direct clash, but if they have challenged us, we, of course, accept it," the minister said. "We are used to sanctions, they have existed nearly forever in one or another kind."

In a phone call initiated by Finland on Saturday, Russian President Vladimir Putin and Finnish President Sauli Niinisto discussed Finland’s decision to join NATO.

Putin described the decision as a mistake that could damage relations between their two countries, according to the Kremlin.

"Putin stressed that abandoning the traditional policy of military neutrality would be wrong, since there are no threats to Finland's security. Such a change in the country's foreign policy course may negatively affect Russian-Finnish relations, which for many years have been built in the spirit of good-neighbourliness and partnership, and have been mutually beneficial," the Kremlin said.

Niinisto's office said Finland initiated the call.

""President Niinisto told President Putin how fundamentally the Russian demands in late 2021 aiming at preventing countries from joining NATO and Russia’s massive invasion of Ukraine in February 2022 have altered the security environment of Finland," Niinisto's office said in a statement.

Niinisto told Putin that every independent nation maximizes its security, according to Niinisto's office.

“The conversation was direct and straight-forward and it was conducted without aggravations. Avoiding tensions was considered important," President Niinisto says.

-ABC News' Somayeh Malekian

U.S. senators, including Senate Minority Leader Mitch McConnell visited Kyiv, Ukrainian President Volodymyr Zelenskyy announced in a video posted online Saturday.

“The visit of the U.S. Senate delegation led by the leader of the Republican minority in the upper house of Congress Mitchell McConnell is a strong signal of bipartisan support for Ukraine from the United States Congress and the American people," Zelenskyy said on Telegram.

Zelenskyy added: "Thank you for your leadership in helping us fight not only for our country, but also for democratic values and freedoms. We really appreciate it.”

-ABC News' Clack Bentson

Russian military commander Vadim Shishimarin, accused of killing a Ukrainian civilian in the Sumy region on Feb. 28, is set to go to trial on May 19, according to Ukraine's prosecutor general Iryna Venediktova.

The 21-year-old soldier allegedly fired his AK-47 at a car driven by a 62-year-old Ukrainian man, killing him at the scene, Venediktova said.

Shishmarin is charged with murder and two counts of robbery.

Prosecutor Andriy Syniuk said Shishmarin has cooperated throughout the investigation.

He is the first member of the Russian military to face charges, Venediktova said.

He could face a life sentence if convicted.

-ABC News' Nadine El-Bawab and Tatiana Rymarenko