PRZEWODOW, Poland — NATO member Poland and the head of the military alliance both said Wednesday there is “no indication” that a missile that came down in Polish farmland, killing two people, was an intentional attack, and that air defenses in neighboring Ukraine likely launched the Soviet-era projectile to fend off a Russian assault that savaged its power grid.

“Ukraine’s defense was launching their missiles in various directions and it is highly probable that one of these missiles unfortunately fell on Polish territory,” said Polish President Andrzej Duda. “There is nothing, absolutely nothing, to suggest that it was an intentional attack on Poland.”

NATO Secretary-General Jens Stoltenberg, at a meeting of the 30-nation military alliance in Brussels, echoed the preliminary Polish findings, saying: “We have no indication that this was the result of a deliberate attack.”

The initial assessments of Tuesday’s deadly missile landing appeared to dial back the likelihood that the incident would trigger another major escalation in the nearly 9-month Russian invasion of Ukraine. If Russia had deliberately targeted Poland, it could have risked drawing NATO into the conflict.

Still, Stoltenberg and others laid overall but not specific blame on Russian President Vladimir Putin’s war.

“This is not Ukraine’s fault. Russia bears ultimate responsibility,” Stoltenberg said.

Before the Polish and NATO assessments, U.S. President Joe Biden had said it was “unlikely” that Russia fired the missile but added: “I’m going to make sure we find out exactly what happened.”

Three U.S. officials said preliminary assessments suggested it was fired by Ukrainian forces at an incoming Russian one. The officials spoke on condition of anonymity because they weren’t authorized to discuss the matter publicly.

That assessment and Biden’s comments at the Group of 20 summit in Indonesia contradicted information earlier Tuesday from a senior U.S. intelligence official who told The Associated Press that Russian missiles crossed into Poland.

Former Soviet-bloc country Ukraine maintains stocks of Soviet- and Russian-made weaponry, including air-defense missiles, and has also seized many more Russian weapons while beating back the Kremlin’s invasion forces.

Ukrainian air defenses worked furiously against the Russian assault Tuesday on power generation and transmission facilities, including in Ukraine’s western region that borders Poland. Ukraine’s military said 77 of the more than 90 missiles fired were brought down, along with 11 drones.

The Kremlin on Wednesday denounced Poland’s and other countries’ initial response to the missile landing and, in rare praise for a U.S. leader, hailed Biden’s “restrained, much more professional reaction.”

“We have witnessed another hysterical, frenzied, Russophobic reaction that was not based on any real data,” Kremlin spokesman Dmitry Peskov said. He added that “immediately, all experts realized that it could not have been a missile linked to the Russian armed forces.”

Still, Ukraine was under countrywide Russian bombardment Tuesday by barrages of cruise missiles and exploding drones, which clouded the initial picture of what exactly happened in Poland and why.

In Europe, NATO members Germany and the U.K. laced their calls for a through investigation of the missile landing with criticism of Moscow.

“This wouldn’t have happened without the Russian war against Ukraine, without the missiles that are now being fired at Ukrainian infrastructure intensively and on a large scale,” said German Chancellor Olaf Scholz.

U.K. Prime Minister Rishi Sunak said: “This is the cruel and unrelenting reality of Putin’s war.”

Ukrainian President Volodymyr Zelenskyy called it “a very significant escalation.” On the other end of the spectrum, China was among those calling for calm and restraint.

Damage from the aerial assault in Ukraine was extensive and swaths of the country were plunged into darkness. Zelenskyy said about 10 million people lost power but tweeted overnight that 8 million were subsequently reconnected, with repair crews laboring through the night. Previous Russian strikes had already destroyed an estimated 40% of the country’s energy infrastructure.

The missile landed in the Polish farming village of Przewodow near the border with Ukraine.

The Russian bombardment also affected neighboring Moldova. It reported massive power outages after the strikes in Ukraine disconnected a power line to the small nation.

Tuesday’s assaults killed one person in a residential building in Ukraine’s capital, Kyiv. It followed days of euphoria in Ukraine sparked by one of its biggest military successes — the retaking last week of the southern city of Kherson.

With its battlefield losses mounting, Russia has increasingly resorted to targeting Ukraine’s power grid, seemingly hoping to turn the approach of winter into a weapon by leaving people in the cold and dark.