President Vladimir Putin said on Wednesday that Russia would achieve its goals in Ukraine by diplomatic or military means, and would seek to expand a "security buffer zone" there.

"First, the goals of the special military operation will undoubtedly be achieved. We would prefer to do this and address the root causes of the conflict through diplomacy," Putin said.

"If the opposing side and their foreign patrons refuse to engage in substantive discussions, Russia will achieve the liberation of its historical lands by military means. The task of creating and expanding a security buffer zone will also be consistently addressed."

Of the regions of Ukraine that Russia has claimed as its own territory, it currently controls Crimea, around 90% of the Donbas region and 75% of Kherson and Zaporizhzhia.

In addition, Russia holds some territory in the adjoining regions of Kharkiv, Sumy, Dnipropetrovsk and Mykolaiv. Putin's comments signaled that Moscow would seek further gains on some of these fronts.

With the war at a key juncture as President Donald Trump pushes hard for a quick peace agreement, Putin said Russia was advancing on all fronts.

But his defense minister, Andrei Belousov, acknowledged that Ukrainian forces were trying to take back control of the northeastern town of Kupiansk - an effort he said was not succeeding.

Ukraine said on Wednesday it had taken 90% of the town, which Russia said it had captured in November.

Putin said people in Europe were being indoctrinated with fears of a war with Russia, and accused their leaders of whipping up hysteria.

"I have repeatedly stated: this is a lie, nonsense, pure nonsense about some imaginary Russian threat to European countries. But this is being done quite deliberately," he said.

Putin has said Russia is not seeking war with Europe, but is ready for war if that is Europe's choice.