“The situation in terms of economic growth is going to be really very depressing, even if the war immediately stops,” he said in a virtual speech to the Peterson Institute for International Economics.

Ustenko repeated his call for European and other governments to cut off Moscow’s access to “blood money” by boycotting Russian oil and natural gas.

“Europeans are still paying to this monster in order to kill our people, innocent people,” he said.

While European nations rely on Russian energy for heat, “I can assure you it’s much, much, much colder in the underground of Ukraine where the people are hidden.”

The official praised the U.S. for halting imports of Russian oil and said he hoped Washington would also help create a “recovery fund” for Ukraine.

Kyiv also could use the approximately $300 billion in Russian central bank reserves frozen as a result of Western sanctions, as well as funds seized from oligarchs who are allies of President Vladimir Putin.

“We have to rebuild the economy,” he said.

The International Monetary Fund (IMF) on Wednesday approved $1.4 billion in fast-disbursing aid for Ukraine, and the World Bank this week released nearly $500 million of what is expected to be a $3 billion financing package.

In addition, the U.S. Congress on Wednesday approved $14 billion in aid for Ukraine.

Asked about the resilience of Ukraine’s financial system, and bank payment operations, Ustenko said: “Look, we are doing, I would say, OK under the current circumstances.”

He said Ukraine’s fiscal reserves are currently at about $27.5 billion, down from about $30 billion before the invasion.

Despite some pressure on the hryvnia currency, Ukrainians in areas not occupied by Russian forces are able to access cash via ATMs and supermarket cashiers without the long lines seen in the first two days of the war, and credit card and other electronic payment systems are working normally, he added.

“Even in those cities surrounded by now by the Russian army…(residents) are able use their cards,” Ustenko said. “(But) what we need most of all is more weapons and ammunition. This is critically important.”