Russian President Vladimir Putin has warned that Western countries’ attempts to phase out Russian gas imports will have a negative impact on their economies. On Thursday, Russian President Putin said European attempts to find alternatives to Russian gas shipments will be “quite painful for the initiators of such policies and then argued that “there is simply no reasonable replacement for it in Europe now.

Meanwhile, Russia on the same day said Ukrainian helicopters had hit residential buildings and injured seven people in the Bryansk region, the latest of a series of cross-border attacks that Moscow has said may trigger a retaliatory attack on Kyiv.

"On April 14, 2022, using two combat helicopters equipped with heavy offensive weapons, military personnel of the Armed Forces of Ukraine illegally entered the airspace of the Russian Federation," Russia's investigative committee said in a statement.

Here are the top developments from the Russia and Ukraine War:

President Joe Biden said top U.S. officials are deciding soon whether to send a senior official to Kyiv in a show of support for Ukraine. "We'll be making that decision soon," Biden told reporters.

Canada will deploy up to 150 military personnel to Poland to support Ukrainians fleeing Russia's war and address a growing refugee crisis, Defense Minister Anita Anand said on Thursday

Russian officials on Thursday said Ukrainian helicopters had hit residential buildings and injured seven people in the Bryansk region, the latest of a series of cross-border attacks that Moscow has said may trigger a retaliatory attack on Kyiv.

Russia's security service said a border post in the Bryansk region had been fired at in the latest reported cross-border attack that Moscow has said may trigger an escalation of the conflict.

The governor of Kharkiv region said four civilians had been killed and 10 wounded in Russian shelling of Kharkiv city on Thursday. Reuters could not verify his remarks.

Russian television broadcasts clips of what it says is the surrender in the besieged port of Mariupol showing unarmed men in military fatigues walking with their hands up towards masked soldiers.

Ukraine says nine humanitarian corridors have been agreed for Thursday to evacuate civilians from eastern cities including Mariupol, while a new prisoner swap meant 30 Ukrainians would be going home the same day.

Ukraine's Kramatorsk and Kostiantynivka are likely to be targeted by Russia for levels of violence seen in other urban centres, British military intelligence says.

President Vladimir Putin will consider a range of measures to bolster Russia's security if Finland or Sweden join NATO, the Kremlin said.

U.S. President Biden said for the first time that Russia's invasion amounts to genocide.

Australia imposed sanctions on 14 Russian state-owned enterprises.

Putin told Austrian Chancellor Karl Nehammer that Austria's supply of gas can still be paid for in euros, Nehammer was quoted as saying.

(With inputs from agencies)