Blasts were heard in Ukrainian capital of Kyiv and in the major city of Kharkiv on Monday morning, Ukraine's State Service of Special Communications and Information Protection said.
Kyiv had been quiet for a few hours prior to that, it said in a brief statement on the Telegram messaging app.
In a separate statement, the agency said a residential building in the city of Chernihiv in northern Ukraine was on fire after being struck by a missile.
Another northern Ukrainian city, Zhytomyr, was hit by missiles overnight, Ukrainian Ground Forces command said on Facebook.
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