KYIV, Ukraine (AP) — Russia’s invading forces have broken into an eighth region of Ukraine, a Ukrainian military official said Wednesday, seeking to capture more ground in their three-year war of attrition as U.S.-led peace efforts struggle to gain traction.

Some Russian troops have entered the villages of Novoheorhiivka and Zaporizke in the eastern Dnipropetrovsk region, a major Ukrainian industrial center next to the Donetsk region where fierce fighting has been taking place, Victor Trehubov, spokesman for local ground forces, told The Associated Press by phone.

Russia’s Defense Ministry claimed earlier this month that its forces had taken the two villages.

But the Russians have not entrenched or built fortifications there, and fighting is continuing in the villages, Trehubov said.

Ukrainian troops are under severe strain as they try to hold back Russia’s bigger army. Military analysts say there is no sign of a looming collapse of Ukrainian defenses and note that Russian forces have been unable to take major towns and cities, but their slow slog through rural areas keeps Ukraine under pressure.

The front line, where tens of thousands of troops on both sides have been killed, snakes along roughly 1,000 kilometers (620 miles) of eastern and southeastern Ukraine, which borders Russia. Russian forces are already in the Sumy, Kharkiv, Luhansk, Donetsk, Zaporizhzhia, Kherson and Mykolaiv regions.