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 forces of Ukraine continue to hold back the enemy’s offensive,” it said.

“Russia has begun a new wave of counteroffensive actions in this direction,” Ukrainian President Volodymyr Zelenskyy said during a planned news conference in Kyiv shortly after the ministry’s statement. “Ukraine has met them there with our troops, brigades and artillery.”