US President-elect Donald Trump has softened his stance on ending the fighting in Ukraine. He had claimed on the campaign trail that the war would be over 24 hours after he takes office.

However, at a news conference in Florida on Wednesday, he said: "I hope to have six months. No, I would think, I hope long before six months."

Trump added that the situation is "much more complicated" and that the fighting could "escalate."

His comments come as casualties on both sides continue to mount. Ukrainian officials said Russian airstrikes in the southeastern city of Zaporizhzhia on Wednesday killed 13 people and injured dozens more.

Meanwhile, the governor of the western Russian region of Saratov said an attack by Ukrainian drones overnight from Tuesday to Wednesday killed two emergency ministry officials.

Defense ministry officials in the UK have been keeping track of the fighting. They say the number of Russian military casualties last year reached 429,600. That was a sharp increase from the previous year.

A Ukrainian military commander says his forces are also suffering a rise in casualties and facing difficulties finding soldiers to replace them. One outlet in the country reported that 1,700 troops have gone AWOL from a newly established brigade.