Who Is Using the S-300 Missile Identified in Poland Strike?

Reports that what was initially alleged to be a Russian missile struck inside Poland's border on Tuesday, killing two people, sparked fears that the ongoing war in Ukraine could escalate into a larger conflict.

Leaders of Poland and NATO have since said that the rocket was probably a stray that was fired by Ukraine to defend itself from a barrage of Russian missile attacks on Tuesday, Reuters reported. Russia has also denied that it intentionally or accidentally struck within Poland's border.

Kremlin spokesperson Dmitry Peskov told reporters Wednesday that Russia carried no blame for what happened and there was no reason for an escalation of the war, according to the Russian-state-owned news agency TASS.

Still, NATO Secretary-General Jens Stoltenberg said in Brussels on Wednesday that Russia, rather than Ukraine, was at fault in the situation since it launched the war and Tuesday's attacks against Ukraine, to begin with.

The fact that the missile likely came from Ukraine instead of Russia may be easing concerns about a potential escalation of Russia's war into an all-out conflict with NATO, even as world leaders continue to chart their response to the incident. But the development was notable all the same because it marked the first time that the deadly invasion directly spilled over into a NATO country in more than eight months of the war.

The S-300, identified as the likely culprit in Tuesday's incident, is a family of Russian-made surface-to-air missile (SAM) systems that are "capable of engaging aircraft and UAVs [unmanned aerial vehicles] in addition to providing some cruise and ballistic missile defense capability," according to the Center for Strategic and International Studies Missile Threat site.

Both Ukraine and Russia have reportedly used the missiles in the course of the war. iNews, citing a Western intelligence report, reported in July that Russia was using Soviet-era S-300 missiles for strikes against land-based targets in Ukraine. That same month, the Ukrainian military's Operational Command South formation said on Facebook that Ukrainian missile and artillery units destroyed a battery of Russian-operated S-300 air defense systems near Zelenotropynske in the southern Kherson region.

Slovakia donated an S-300 system to Ukraine in April, and in return, the U.S. provided Slovakia with a Patriot missile system that was manned by U.S. service members. U.S. defense officials praised the donation and said that the system was meant to help bolster Ukraine's air defenses so it can better protect itself from Russian attacks.

Ukraine had already had its own S-300 system even before the donation, The New York Times reported.

When Russia was initially believed to be behind the missile that landed in Poland, this sparked conversations on whether NATO could invoke Articles 4 or 5 of its charter. The principle of collective defense, which means that an attack against one NATO member is considered an attack against all NATO members, is enshrined in Article 5. Article 4 allows for any member state to seek consultations with the rest of the defensive alliance, especially when "related to the security of a member country." It does not guarantee that NATO will take action in a given situation.

Dr. Michael Butler, associate professor of political science at Clark University, told Newsweek that in light of the indications that it was a stray Ukrainian missile rather than a Russian attack, invoking Article 4 could still give NATO the chance to discuss how to handle similar instances in the future.

This includes "possibly establishing new rules of engagement and where the 'red line' might be going forward," he said.

"If, as by all indications it appears, this was not an intentional Russian strike on a NATO member, that's the best case scenario...but not one that Poland, the U.S., or any other NATO member can bank on going forward," Butler said."There's a reason why the prospect of this being an intentional Russian strike was so immediately plausible—Russia has repeatedly demonstrated itself to be a rogue state that does not respect international norms, loathes NATO, and fully understands the maxim of 'divide and conquer.'"

Ukrainian President Volodymyr Zelensky initially alleged Tuesday that it was a Russian missile that hit Poland and called it a "really significant escalation." Now that Zelensky's accusation is likely false, Butler does not believe that the Ukrainian president will face a backlash among his Western allies for how he first responded to the news.

"While Zelensky might have a strategic reason for representing the incident in this way—to further engage NATO and reaffirm the continued severity of the war for them, as well as for Ukraine—we are talking about a war-time leader trying to process an enormous volume of information and intelligence on the fly, in the context of a country whose entire power grid was just taken down by a systematic barrage of missiles," Butler said.

Newsweek reached out to the defense ministries of Russia and Ukraine for comment.

Update 11/16/22, 1:30 p.m. ET: This article was updated with comments from Dr. Michael Butler.