This year will be a game changer and the Armed Forces of Ukraine (AFU) must win this war as they are fighting to defend this country, Defense Minister of Ukraine Oleksiy Reznikov said in an interview with Fox News.

"My gut feeling is we will win this war because we are fighting for our country," he said.

The minister also described the current maneuvers of the Ukrainian troops as "some kind of preparatory operation," acknowledging the Russians had built up "very strong defensive lines."

He admitted early expectations were "overestimated" for the offensive, and Ukraine is very careful when it puts its brave and motivated fighting men and women in harm's way.

"We try to save their lives," Reznikov said. He described the Russian approach to using its troops as a "meat grinder."

He added, however, that once it fully gets going, it will be successful and "one step closer to victory."

Speaking about Russian President Vladimir Putin's attempts to play the nuclear card, Reznikov said: "I think, for me, personally, it sounds like a bluff. I think the civilized world has arguments against that to persuade him."