Russian aerial attacks overnight and during daylight Wednesday killed two civilians and wounded six in a central Ukraine city, local officials said, while the Kyiv and Odesa regions bore the brunt of Moscow's latest attacks.

The air war between Russia and Ukraine has intensified as the conflict stretches into its fifth year following Moscow's invasion of its neighbor.

The front line in eastern and southern Ukraine remains largely deadlocked, and U.S. efforts to negotiate a settlement have yet to produce a path to peace.