The United States agrees with the Polish President's assessment that the explosion in the east of the country appears to have been the result of a Ukrainian air defense force missile crash, but this does not absolve Russia of responsibility for firing missiles at Ukraine's civilian infrastructure, National Security Council spokeswoman Adrienne Watson stated, the Voice of America reports.

Watson said the U.S. has full confidence in the Polish government's investigation and thanks Warsaw for its professional approach.

"We will not get ahead of their work and remain in close touch with our Polish counterparts, as we are still gathering information. We have seen nothing that contradicts President Duda’s preliminary assessment that this explosion was most likely the result of a Ukrainian air defense missile that unfortunately landed in Poland. We will continue to assess and share any new information transparently as it becomes available. We will also continue to stay in close touch with the Ukrainians regarding any information they have to fill out the picture."

Nevertheless, Watson said, whatever the final conclusions, "it is clear that the party ultimately responsible for this tragic incident is Russia, which launched a barrage of missiles on Ukraine specifically intended to target civilian infrastructure. Ukraine had — and has — every right to defend itself."

The NSC representative expressed solidarity with the people of Ukraine and offered condolences for the losses that Ukrainians suffered as a result of these "barbaric airstrikes."

"We know that millions more Ukrainians remain without power, water and basic necessities as a result.  Our thoughts and prayers go out again to the loved ones of the two Polish citizens tragically killed," Watson added.