U.N. Secretary-General Antonio Guterres said Thursday that in war, “the highest price is paid by civilians,” as he visited sites outside the Ukrainian capital ahead of talks with President Volodymyr Zelenskyy.

The areas Guterres toured included Borodianka and Irpin, as well as Bucha, where the bodies of civilians were found after Russian forces withdrew from the area one month ago. Those discoveries prompted calls for investigations of possible war crimes, and Guterres on Thursday encouraged Russia to cooperate in probes by the International Criminal Court.

“I fully support the ICC and I appeal to the Russian Federation to accept, to cooperate with the ICC,” Guterres said. “But when we talk about war crimes, we cannot forget that the worst of crimes is war itself.”

The U.N. chief said after arriving in Ukraine that he wanted to “expand humanitarian support and secure the evacuation of civilians from conflict zones,” topics that were part of his talks earlier this week with Russian President Vladimir Putin and Foreign Minister Sergey Lavrov.

“The sooner this war ends, the better – for the sake of Ukraine, Russia, and the world,” Guterres tweeted.

US aid

U.S. President Joe Biden is due to speak Thursday about additional support for Ukraine, as he sends to Congress a proposed package of security, economic and humanitarian assistance.

White House press secretary Jen Psaki told reporters Wednesday that the package would be similar in focus to earlier rounds of aid to “help address a range of the needs the Ukrainians have.” She did not specify the size of the proposed assistance.

Biden is also sending to Congress a request for a separate set of actions to tighten sanctions, to make more efficient the process of seizing assets of sanctioned oligarchs, and to enable taking proceeds from seizures and forfeited funds and sending them to Ukraine to “remediate harms of Russian aggression.”

The proposal would also include working more closely with international partners to “recover assets linked to foreign corruption,” and to extend the amount of time to pursue money laundering prosecutions from five years to 10 years.

A White House statement said the measures would “enhance the United States government’s authority to hold the Russian government and Russian oligarchs accountable for President Putin’s war against Ukraine.”

Separately, Congress could also send “lend-lease” legislation, further freeing the flow of weapons, to Biden’s desk for a signature as early as the end of this week.

Pentagon press secretary John Kirby on Wednesday cited the ongoing flow of weapons and aid in the success Ukraine has maintained in the battle against Putin’s unprovoked invasion.

Putin warned against Western intervention in Ukraine as he spoke to lawmakers in St. Petersburg on Wednesday.

“If someone intends to intervene in the ongoing events from the outside, and create strategic threats for Russia that are unacceptable to us, they should know that our retaliatory strikes will be lightning-fast,” Putin said. “We have all the tools for this, things no one else can boast of having now. And we will not boast, we will use them if necessary. And I want everyone to know that.”

NATO expansion

Military support for Ukraine, either pledged or provided already by NATO allies, has reached $8 billion, NATO Secretary General Jens Stoltenberg said Thursday.

Russia’s invasion of Ukraine has pushed Finland and Sweden to consider applying to be members of the NATO military alliance, and Stoltenberg said if they do choose to take that step, the process could be completed quickly.

“It is, of course, for Finland and Sweden to decide whether they would like to apply for membership in NATO or not. But if they decide to apply, Finland and Sweden would be welcomed with open arms to NATO,” Stoltenberg told reporters in Brussels.

Russia has expressed opposition to prospective NATO membership for Finland and Sweden, saying if they do join, Russia will deploy nuclear weapons and hypersonic missiles to Kaliningrad.

“This is fundamentally about the right of every nation in Europe to decide its own future,” Stoltenberg said. “So when Russia tries to threaten, to intimidate Finland and Sweden from not applying, it just demonstrates how Russia is not respecting the basic right of every nation to choose its own path.”

Russian energy

Ukrainian presidential adviser Mykhailo Podolyak said Thursday “it’s a matter of time” before an embargo is imposed on Russia’s key energy industry.

While European nations have taken steps to reduce or eliminate their reliance on Russian oil and gas, replacing those supplies and potential economic hits at home have made some leaders express caution about how quickly to proceed down that path as Ukrainian officials called for an embargo.

Podolyak tweeted that avoiding Russian energy supplies is both a moral issue and a matter of Russia ceasing “to be a reliable and predictable partner in the eyes of the world.”

“Switching to alternative supply channels quickly will be expensive, but not as expensive as not doing so,” Podolyak tweeted. “In the medium term, Moscow will face total economic and political isolation. As a result, poverty, the scale of which Russia has not seen yet.”

His comments came a day after Russia’s Gazprom halted natural gas supplies to Poland and Bulgaria.

Gazprom said Wednesday that Poland and Bulgaria had not met Russia’s demand to pay for natural gas in rubles. The company said four unnamed natural gas buyers have paid Russia in rubles, and 10 European companies have created ruble accounts to make payments in the Russian currency, Bloomberg News reported.

Polish President Andrzej Duda said the Russian gas cutoff violated “basic legal principles,” while Bulgarian Energy Minister Alexander Nikolov said gas was being used as a “political and economic weapon.”

National security correspondent Jeff Seldin contributed to this report. Some information came from The Associated Press, Reuters and Agence France-Presse.