Russia's Defense Ministry spokesman on Thursday claimed it did not carry out the attack on a children's hospital in Mariupol, which Ukrainian officials said killed 3 people and injured 17.

Russian officials, including its foreign minister, had earlier said they targeted the hospital, claiming it was being used as a firing position by Ukrainian nationalists.

Russia’s Defense Ministry spokesman claimed that the devastating bombing was staged.

-ABC News' Patrick Reevell

Secretary of State Antony Blinken spoke to his Polish counterpart, Foreign Minister Zbigniew Rau, to discuss joint security and humanitarian efforts in Ukraine, specifically Russia's attacks on civilian population centers, according to the U.S. State Department.

The two met on the Polish-Ukrainian border Saturday. The phone call comes amid disagreements over sending fighter jets to Ukraine after Poland said it is willing to send the jets to a U.S. base in Germany, the Pentagon said the move could be seen by Russia as "escalatory."

"Secretary Blinken and Foreign Minister Rau discussed ongoing diplomatic efforts, including sanctions, to stop Putin’s war of aggression. The Secretary reiterated the United States’ steadfast support for Ukraine’s sovereignty and territorial integrity," the U.S. State Department said in a release.

The State Department added, "The Secretary and Foreign Minister also discussed the continued importance of providing security assistance to Ukraine."

The call comes as Vice President Harris visits Poland, and after Defense Secretary Lloyd Austin called his Polish counterpart on Wednesday.

Blinken also spoke to Ukrainian Foreign Minister Dmytro Kuleba Wednesday, ahead of his talks with Russian Foreign Minister Sergey Lavrov.

-ABC News' Conor Finnegan

Senate Minority Leader Mitch McConnell decried the Biden administration on the Senate floor Thursday over the "bizarre argument" that played out in public after the U.S. refused to accept Poland’s offer to donate MiG-29 aircrafts to Ukraine’s military resistance.

McConnell accused the Biden Administration of "contradicting themselves" and of proving incapable to coordinate assistance efforts with NATO allies.

"The world needs President Biden and his team to be leading, taking the initiative and shaping circumstances, calmly soberly, but with confidence and decisiveness," McConnell said. "They seem to be trapped in a cycle of passivity indecision self-determines."

-ABC News' Trish Turner

Russian Defense Ministry spokesperson Igor Konashenkov held another press briefing in which he accused NATO countries of committing war crimes.

Konashenkov claimed Thursday that mercenaries from the U.K. and U.S. are increasingly attacking Russian military medics who are accomplishing humanitarian missions in Ukrainian territory.

"Attacks on Russian medics and special medical vehicles by the Ukrainian nationalists and mercenaries that came earlier from the U.S., Britain and Europe to Ukraine have become more frequent over the past few days," Konashenkov said.

Konashenkov also denied reports that the Russian military had carried out a strike on a children’s hospital in Mariupol on Wednesday, dismissing reports on the matter as an "an information provocation staged by the Kyiv regime."

"The alleged airstrike that took place is a completely staged provocation in order to maintain the anti-Russian public outcry in the Western audience," he alleged.

Russian forces have destroyed nearly 3,000 military installations in Ukraine since the invasion began, Konashenkov claimed. In the last 24 hours, 68 installations, including two sites of the Ukrainian troop control system, 12 material and technical support centers and three Osa air defense missile systems, were obliterated, he said.