Ukraine is in for a "very ugly period" as Russia's war in the country approaches one year, international relations expert Robert Patman says.

Russia invaded on February 24 last year and a fresh Russian offensive is expected in the next few weeks.

Speaking to Breakfast this morning, Patman said while Ukraine may be militarily superior to Russia, the Russian's have an advantage in manpower and artillery.

"What I think, for the next six months, the war is going to intensify. The Ukrainians over time will become more competitive but I don't think the picture looks good for Mr Putin because, really he's asking a lot of these ill-prepared troops, which are being introduced into a battle zone against a very professional, well organised army that the Ukrainians have."

Asked if he thinks there's opportunity for Ukraine to negotiate with Russia, Patman said it's unlikely.

"The scope for diplomacy has diminished dramatically, Mr Putin hasn't shown any signs, serious signs, in wanting to negotiate.

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"He'd really love to hang on to the territory and it seems like with this new offensive, he's planning to expand operations."

He says on the other hand, for those who are arguing the invasion is a breach of international law, there's nothing to negotiate.

"The danger in negotiation, it sounds good but what does it mean in practice, it means that a blatant aggressor will be given some reward for seizing territory from a neighbouring state.

"And so I think the liberals have won the argument against the so-called realists and they are arguing that if the Ukrainians are given sufficient support, they themselves will decide the outcome, they will eject Russian troops from Ukrainian territory."

Asked if there's any chance a negotiation could avoid a nuclear war from Russia, Patman said most people believe it's "nuclear sabre-rattling" and shows Putin's weaknesses, rather than his strengths.

"That is certainly the argument that's been put forward, the thing is, Mr Putin threatened nuclear weapons at the outset of this conflict.

"He's not winning the war on the ground and that's why he's making such threats."