Sept. 14 (UPI) -- Romania has claimed a Russian drone entered its airspace Saturday near Ukraine's southern border, a move Ukrainian President Volodymyr Zelensky called an expansion by Russia in the ongoing war.

"The Russian military knows exactly where their drones are headed and how long they can operate in the air," a social media statement by Zelensky said. "Their routes are always calculated. This cannot be a coincidence or a mistake or the initiative of some lower level commanders."

Romania is the second NATO country to report such an incursion. On Wednesday, Poland said it had shot down three drones that had breached its airspace, according to the BBC.

Romania said it detected the Russian drone when a pair of F-16 jets were monitoring its border with Ukraine, according to a statement from the Romanian defense ministry.

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