US President Joe Biden is due to speak with his Ukrainian counterpart Volodymyr Zelensky on Sunday as tensions soar in the region between the West and Russia, whom the former is accusing of planning a military invasion of its western neighbor.

Russia is facing US-European allegations of having plans to invade Ukraine, in addition to a military buildup on their shared borders, which they claim amounts to 100,000 Russian troops.

The secretary of the Ukrainian Security and Defense Council said Thursday his country believed there was no immediate threat of a major Russian invasion. Similarly, Kyiv had denied in November Western reports of a Russian military buildup near its eastern border.

President Vladimir Putin had said earlier this month Moscow pursues a peaceful foreign policy; however, it had the right to defend its security.

US President Joe Biden and his Russian counterpart Vladimir Putin discussed the rising tensions in a phone call on Wednesday.

During the call, Biden warned Russian President Vladimir Putin of severe consequences if Moscow invades Ukraine.

"I'm not going to negotiate here in public, but we made it clear he cannot - I'll emphasize, cannot - invade Ukraine," Biden said Friday.

The US leader told reported he had "made it clear to President Putin that we will have severe sanctions, we will increase our presence in Europe, with NATO allies" if Russia invades its western neighbor.

Biden will "reaffirm US support for Ukraine's sovereignty and territorial integrity, discuss Russia's military build-up on Ukraine's borders, and review preparations for upcoming diplomatic engagements to help de-escalate the situation in the region," in Sunday's call with Zelensky, the White House said.

Zelensky tweeted: "Look forward to talking again with [Biden] this Sunday to coordinate our steps for the sake of peace in Ukraine and security in Europe."

As we have agreed with our Strategic Partner 🇺🇸, nothing about 🇺🇦 without 🇺🇦. Look forward to talking again with @POTUS this Sunday to coordinate our steps for the sake of peace in Ukraine and security in Europe

— Володимир Зеленський (@ZelenskyyUa) December 31, 2021

Russia has been demanding a written commitment that Ukraine would never be able to join NATO and that the alliance would not place any military equipment in certain countries in the region surrounding Russia.

The West has refused Russia's demands of a guarantee, saying NATO's principle stipulates that membership is open to any qualifying country. However, ahead of the call, the White House said Biden would tell Putin a diplomatic path remains open.

The Kremlin sees that it is best for Russian security that the alliance does not expand eastward and that Russia does not have any Western military activity in its vicinity.

Russia has repeatedly denied the Western allegations of intending to invade its western neighbor, and Moscow's Foreign Intelligence Service accused the US State Department of spreading false information about the alleged troop buildup.

Moscow and Washington will hold in-person negotiations in Geneva, Switzerland, next month, and ahead of Thursday's call, both parties said they were ready to listen.

US Secretary of State Antony Blinken spoke Friday with NATO chief Jens Stoltenberg. Following their conversation, Blinken urged Russia to "engage meaningfully" in the upcoming talks on the tense standoff between Moscow and Kiev.

Stoltenberg said that NATO was "united" and "prepared for dialogue."