WATCH: State Department speaks on reports of Russian missiles hitting Poland

The State Department says the United States is working with the Polish government to determine the extent of U.S. intelligence reports that Russian missiles crossed into NATO member Poland, where two people were killed.

Watch the briefing in the player above.

State Department Principal Deputy Spokesperson Vedant Patel, told reporters Tuesday “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.”

Russia pounded Ukraine’s energy facilities with its biggest barrage of missiles yet, striking targets across the country and causing widespread blackouts.

A second person told The Associated Press that apparent Russian missiles struck a site in Poland about 15 miles from the Ukrainian border.

If confirmed, the strike would  The strike marks the first time in the war that Russian weapons have come down on a NATO country.

“We of course are ready to stand with our NATO allies and partners,” Patel said. “We’re working with our partners and the Polish government and our NATO partners to get more information.”

The Russian Defense Ministry denied being behind “any strikes on targets near the Ukrainian-Polish border” and said in a statement that photos of purported damage “have nothing to do” with Russian weapons.

READ MORE: Poland says Russian-made missile fell on its soil, killing 2

Polish government spokesman Piotr Mueller confirmed that an explosion had killed two people and said some military units were put on alert while officials investigated.

Polish media reported that the strike took place in an area where grain was drying in Przewodów, a village near the border with Ukraine.

Meanwhile, the U.S. is imposing sanctions on firms and entities accused of being involved in the transfer of Iranian drones to Russia for use in Vladimir Putin’s ongoing invasion of Ukraine.

The penalties and diplomatic restrictions come as part of the most recent effort by the United States to disrupt Russia’s military supply chain and procurement network.

They also cut at the growing relationship between Russia and Iran, two politically and economically isolated nations.

The Treasury Department is sanctioning a company that the U.S. says designs and produces drones used by Russian forces in Ukraine as well as several firms that are said to facilitate the transfer of Iranian drones to Russia.

Also, Israel’s departing prime minister says Israel will not participate in an American investigation into the fatal shooting of a prominent Al Jazeera correspondent in the occupied West Bank.

Yair Lapid on Tuesday was responding to reports that the U.S. Justice Department was opening a probe into the killing of 51-year-old Shireen Abu Akleh last May in Jenin, a Palestinian city.

Akleh was a Palestinian-American journalist.

During Tuesday’s briefing Patel said,”Whether the Department of Justice takes part in any law enforcement activity on any subject under the sun, that is for them to speak to. That is not an equity here for the State Department. That is not something I’m going to be able to speak to.”

A Justice Department spokesman had no comment. But an FBI probe into the actions of an ally would mark a rare — if not unprecedented — step, threatening to strain close ties between the countries.

Lapid said Israeli soldiers will not be investigated by any foreign country, “however friendly.”