Romania said a Russian drone violated its airspace, the second country to report such an invasion.

Romanian fighter jets carried out Russian attacks in Ukraine on Saturday and were able to track drones near Ukraine’s southern border, the Ministry of Defense said in a statement.

Ukrainian President Volodymyr Zelensky said the invasion was not a mistake – it was “a clear expansion of the Russian war.” Moscow has no comment on Romania’s claims.

On Wednesday, Poland said it had shot down at least three Russian drones entering the airspace.

The Romanian Ministry of Defense said in a statement that when F-16 jets monitored their border with Ukraine twice, it discovered Russian drones after “Russia’s Ukrainian infrastructure on the Danube.”

Before the radar disappeared, the drone was detected 20 kilometers (12.4 miles) southwest of the village of Chilia Veche.

But it did not fly over densely populated areas or pose an imminent danger, the ministry said.

Poland also responded to Saturday’s concerns about Russian drones.

“The preventive role of aviation – Poland and the Allies have begun,” Prime Minister Donald Tusk said in a post on X.

“The ground air defense system has reached its highest state of readiness.”

Earlier this week, the Russian Ministry of Defense said there were no plans to target facilities on Polish soil.

Russia’s close ally Belarus said the drone entering Polish airspace on Wednesday was an accident after their navigation system was blocked.

To cope with the latest invasion, President Zelensky said the Russian military “knows exactly where their drones are going and when they operate in the air.”

He has been asking Western countries to tighten sanctions on Moscow.

U.S. President Donald Trump also weighed airspace violations earlier this week, saying he was “prepared” to impose tougher sanctions on Russia, but only if NATO countries meet certain conditions, such as stopping purchases of Russian oil.

Russia began a full-scale invasion of Ukraine in February 2022 and made slow progress on the battlefield.

Trump has been working to end the war, but Russian attacks on Ukraine have intensified the attack on Ukraine since last month’s summit with Trump in Alaska.