Russia's "massive" military losses in Ukraine are unsustainable, NATO Secretary General warns, as conflict set to enter fourth year with no clear end in sight.

Ukraine's new defense minister says wide-scale desertions and draft-dodging are major challenges as Russia's invasion continues.

Wide-scale desertions and two million draft-dodgers are among a raft of challenges facing Ukraine's military as Russia presses on with its invasion of its full-scale neighbour after almost four years of fighting,

U.S. President Donald Trump told Reuters that Ukraine - not Russia - is holding up a potential peace deal, rhetoric that stands in marked contrast to that of European allies, who have consistently argued Moscow has little interest in ending its war in Ukraine.

Conflict-related violence killed at least 2,514 civilians last year, the UN's monitoring mission in Ukraine said.

The European Union plans to allocate most of a new loan program to Ukraine's military needs over the next two years.

The United States accused Russia of "dangerous and inexplicable escalation" after new attacks on Ukraine's energy and civilian infrastructure.

Russia says it used its new Oreshnik hypersonic missile and other weapons in a massive strike on Ukraine​. Ukrainian President Zelenskyy says a drone hit the Qatar embassy.

Ukraine's chief of defense estimated Wednesday that 200,000 soldiers have gone absent without official leave during an address to parliament.