Russian troops launched an armored ground attack on Ukraine’s northeast Friday, in what Kyiv said was a major new offensive it had been expecting for months.

Ukraine’s Defense Ministry said it was rushing reserve units to the Kharkiv border region after a Russian effort to break through its defense lines backed by armored vehicles and artillery.

The ministry said in a statement that the dawn attacks had been repulsed, but that “battles of varying intensity” continued. “The defense…