Updated

NATO Secretary-General Jens Stoltenberg on Wednesday said a preliminary investigation suggested that the missile that fell in Poland and killed two on Tuesday was likely from Ukraine’s air defense system, but said Russia was "ultimately responsible" for the deaths.

"This is not Ukraine's fault," he told reporters. "Russia bears reasonability for what happened yesterday because this is a direct result for the ongoing war."

"Ukraine has the right to shoot down those missiles that target Ukrainian cities," he added. 

NATO Poland Ukraine

NATO Secretary General Jens Stoltenberg speaks at the NATO headquarters, Wednesday, Nov. 16, 2022 in Brussels. Ambassadors from the 30 NATO nations gathered in Brussels Wednesday for emergency talks after Poland said that a Russian-made missile fell on its territory, killing two people. (AP Photo/Olivier Matthys)

POLISH PRESIDENT SAYS 'NO PROOF' MISSILE THAT LANDED IN NATO TERRITORY WAS FIRED BY RUSSIA

Concerns mounted Tuesday after one anonymous U.S. official told the Associated Press that a Russian missile landed in NATO territory and prompted leaders from the military alliance to scramble to discover what happened. 

President Biden and Western leaders have repeatedly warned Russia against expanding its war effort in Europe have vowed to defend "every inch" of NATO territory – sparking concern the missile strike could prompt a massive escalation. 

Watch Stolbenberg's remarks:

Stoltenberg attempted to ease concerns regarding any attempt by Russia to purposely hit NATO nations and said the alliance has constant land, air and sea-based defense systems on alert.

But reporters questioned why the rocket that killed two yesterday was not blocked by one of these defenses. 

Poland missile investigation

A policeman talks to a driver on the street near the site where a missile strike killed two men in the eastern Poland village of Przewodow, near the border with war-ravaged Ukraine on Nov. 16, 2022.  (WOJTEK RADWANSKI/AFP via Getty Images)

BIDEN SAYS MISSILE KILLING 2 PEOPLE IN POLAND WAS 'UNLIKELY' FIRED FROM RUSSIA IN 'MINDS OF THE TRAJECTORY'

"Attacks, ballistic missiles, cruise missiles have special characteristics which we follow and monitor and then we make a judgment whether it’s an attack or whether it’s something else," Stoltenberg told reporters.  "That missile [didn’t] have the characteristics of an attack."

Stoltenberg said that NATO allies offered their "deepest condolences on the tragic loss of life" during a Wednesday meeting, but held firm on their position in backing Kyiv.

"They expressed their strong solidarity with our valued ally Poland and made clear that we will continue to support Ukraine in its right to self-defense," he added. "Russia must stop this senseless war."

Poland missile

Members of the Police searching the fields near the village of Przewodow in the Lublin Voivodeship, seen on Nov. 16, 2022, in Przewodow, Poland. (Artur Widak/Anadolu Agency via Getty Images)

CLICK HERE TO GET THE FOX NEWS APP

The NATO chief said defense leaders would address bolstering Ukrainian air defense systems in a meeting with the Ukraine Defense Contact Group Wednesday in an attempt to prevent further accidents of this nature, but also as Russia ramps up its air raids while its troops flag on the ground. 

"The best way of preventing anything like this from happening again, is for Russia to stop this war," Stoltenberg concluded.