Russia-Ukraine updates: Putin suspends key US-Russia nuclear treaty in speech denouncing West

Polish President Andrzej Duda said Tuesday night that a rocket that landed near the Polish-Ukrainian border, killing two Polish citizens, may have been Russian-made. Though he said that there is no conclusive evidence at this time of who launched the missile and that an investigation is underway.

Duda said he has also spoken with NATO Secretary General Jens Stoltenberg and President Joe Biden.

Stoltenberg said earlier that NATO is monitoring the situation.

President Joe Biden spoke by phone with Polish President Andrzej Duda and "expressed deep condolences for the loss of life in Eastern Poland," according to the White House.

Biden "offered full U.S. support for and assistance with Poland's investigation" and the two agreed "they and their teams should remain in close touch to determine appropriate next steps as the investigation proceeds," the White House said.

Polish officials confirmed that two Polish citizens were killed in an explosion Tuesday in the area of Hrubieszów. They were the owner of a granary that was stuck and a tractor driver who was transferring corn to the facility, according to local officials.

-ABC News' Ben Gittleson and Tomek Rolski

The White House said Tuesday it has asked Congress for $37.7 billion in additional funding for Ukraine.

The funding would include defense support and humanitarian assistance and be for the rest of the current fiscal year, which runs until Sep. 30, 2023, according to the White House.

"Together, with strong, bipartisan support in the Congress, we have provided significant assistance that has been critical to Ukraine’s success on the battlefield -- and we cannot let that support run dry," Shalanda Young, the head of the White House budget office, said in a letter to House Speaker Nancy Pelosi Tuesday on the funding request.

-ABC News' Ben Gittleson

State Department officials are working to determine the circumstances surrounding the reported strike in Poland, Principal Deputy spokesperson Vedant Patel told reporters.

Calling the reports "incredibly concerning," Patel said they were in close communication with the Polish government and other NATO allies to "gather more information."

"We can't confirm the reports or any of the details at this time. But I can assure you we will determine what happened and what appropriate next steps would be," he said during a briefing Tuesday afternoon.

U.S. national security adviser Jake Sullivan has spoken with Chief of the National Security Bureau of Poland Jacek Siewiera, according to White House National Security Council spokesperson Adrienne Watson.

"We've seen the reports out of Poland and are working with the Polish government to gather more information," Watson said in a statement, also adding that the White House cannot confirm the reports or any details at this time.

President Joe Biden has been briefed on the reports and will be speaking with Polish President Andrzej Duda "shortly," the White House said.

-ABC News' Shannon K. Crawford and Ben Gittleson