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Evgeniy Maloletka, Associated Press
A Ukrainian soldier looks at a part of a wrecked APC at the checkpoint in Krasnyi Lyman, eastern Ukraine, Saturday, July 5, 2014. Ukraine's forces claimed a significant success against pro-Russian insurgents on Saturday, chasing them from one of their strongholds in the embattled east of the country. Rebels fleeing from the city of Slovyansk vowed to regroup elsewhere and fight on.

DONETSK, Ukraine — Pro-Russian insurgents driven out of their stronghold in eastern Ukraine have converged on the city of Donetsk, where their commander says they will regroup to continue their fight against the Ukrainian government.

Ukrainian troops forced the rebels out of their stronghold of Slovyansk on Saturday, suggesting the government may finally be making gains in the months-long battle against the insurgency.

Rebels from Slovyansk and other towns taken over by the Ukrainian army were seen Sunday milling around central Donetsk, a major industrial city in the eastern region where the insurgents have proclaimed the separatist Donetsk People's Republic.

Igor Girkin, the defense minister of the separatist republic, said in a video interview with the Russian television channel Life News that he was in Donetsk and would lead the fight from there.