Pentagon received no information about Ukraine's Kursk offensive

A senior defense official said Ukraine did not inform the U.S. military about its surprise cross-border incursion into the Kursk region of southern Russia, nor did it inform the U.S. of its long-term plans for the follow-up to the move.

“We didn't get any advance notice,” the official said Wednesday. “What the Ukrainians managed to do was operational security, and that's something I think we should take credit for. The Russians were definitely surprised.”

Since invading Russian territory on August 6, Ukrainian forces claim to have captured 390 square miles of land. This would be the largest attack on Russia since World War II. The surprise attack raises questions about the value of the offensive and how long Ukraine can hold onto the captured land.

“I know their concern was to protect the area without the Russians attacking. From that perspective, they have done what they could,” the official said.

However, the US is unclear about Ukraine's overall goals after the invasion. The official said the Pentagon is asking the Ukrainians “what their real intentions are in the long term and what role that will play in future negotiations.”

Asked about the possibility of a counter-escalation, the official said Russia had “done some things to support its citizens in particular in that area, but there were no significant major movements.”

On Wednesday, Ukrainian forces advanced even deeper into Russia, claiming to have captured 100 soldiers and destroyed a Russian Su-34 jet, a type of jet used to drop glide bombs over Ukraine.

Ukrainian officials say the new land would help protect the country's borders from Russian attacks by creating a buffer zone.