(NewsNation) — Competing claims have left uncertainty over who was behind a cross-border attack in the Belgorod region of Russia this week, a situation one former Marine colonel says Ukraine stands to benefit from in the war.

Moscow blamed the raid that began Monday and ended Tuesday on Ukrainian military saboteurs. Kyiv portrayed it as an uprising against the Kremlin by Russian partisans. It was impossible to reconcile the two versions, to say with certainty who was behind the attack or to ascertain its aims.

In assessing the attack, retired Col. Brendan Kearney, who served as chief of staff for Marine Corps Forces Europe and Africa, said the attacks “dramatically increase” Russia’s difficulties in defending its border territory.

“Up until the fall of the Soviet Union, there really wasn’t a border, so Ukrainians are as comfortable in Russia as the Russians are … in Ukraine,” Kearney said Tuesday on “CUOMO.”

Such cross-border attacks embarrass the Kremlin and highlight the struggles it faces in its bogged-down invasion of Ukraine.

Ukrainian President Volodymyr Zelenskyy has repeatedly denied his military is operating on Russian territory, maintaining that Ukraine fights “for peace, not for war.”

“The Ukrainians have been very careful to abide by the guidelines, the agreement that they made, that they will not use any U.S. or other NATO weapons inside Russia,” former U.S. Ambassador to Ukraine Bill Taylor said Tuesday on “CUOMO.” “They have hit inside Russia before, as we know, not with NATO weapons, not with U.S. weapons. They’ve used their own to go deep into Russia and attack airfields, so I think that understanding is still intact.”

The Belgorod region has witnessed sporadic spillover from the war, which Russia started by invading Ukraine in February 2022.

Far from the 932-mile front line in southern and eastern Ukraine, Russian border towns and villages regularly come under shelling and drone attacks, but this week’s attack is the second in recent months that also appears to have involved an incursion by ground forces.

The attack comes after Russian forces claimed control of the city of Bakhmut, which had been under siege for months. Ukraine has claimed it still holds a small portion of the city.

Nonetheless, Kearney said the fight for the city won’t mean much for Russia in the long run.

“Bakhmut poses no tactical, no operational nor strategic value whatsoever. … If Russia wanted to conduct a spoiling attack to disrupt this anticipated Ukrainian offensive, this was the wrong place to do it … and if that was their intention, they failed,” Kearney said. “They win a little battle, but once that offensive starts … no one’s going to remember Bakhmut. It’ll be a paragraph in the history of this campaign.”

The Associated Press contributed to this report.