A Russian invasion of Ukraine could happen at any moment, a defence minister has warned.

Armed Forces Minister James Heappey has described the massing of roughly 130,000 Russian troops along the Ukrainian border as a "credible force set to do something imminently".  It comes after Defence Secretary Ben Wallace compared diplomatic efforts to prevent a Russian invasion of Ukraine to appeasement as he said it is "highly likely" Vladimir Putin will order an attack despite the concerted talks to avert war.

China has joined Russia in opposing further Nato expansion as the two countries move closer together in the face of Western pressure.

Moscow and Beijing issued a statement showcasing their agreement on a raft of issues during a visit by Russia's Vladimir Putin for the Winter Olympics. Mr Putin claims Western powers are using the Nato defence alliance to undermine Russia.

It comes amid tensions over Ukraine, which he denies planning to invade. Some 100,000 Russian troops remain at the border with Ukraine, which is a former Soviet republic. Mr Putin, who has written that Russians and Ukrainians are "one nation", has demanded that Ukraine be barred from joining Nato. While the lengthy joint statement did not refer directly to Ukraine, the two countries accused Nato of espousing a Cold War ideology.

The talks, which the Kremlin said were "very warm", were held ahead of the Games opening ceremony. It was the first time the leaders have met face-to-face since the start of the pandemic. "Friendship between [Russia and China] has no limits, there are no 'forbidden' areas of cooperation,"

The UK Defence Secretary said there were individuals already in Ukraine "linked to the Russian state in ways that are not conventional".

Russia may already have personnel in place in Ukraine to assist with an invasion, the UK Government believes. Defence Secretary Ben Wallace told MPs there were individuals already in Ukraine "linked to the Russian state in ways that are not conventional" and "that should give cause for concern". He added: "We are becoming aware of a significant number of individuals that are assessed to be associated with Russian military advance force operations that currently are located in Ukraine."

It comes as concerns over a potential Russian invasion into Ukraine continue to increase. Moscow has massed an estimated 100,000 troops near the border with Ukraine. Mr Wallace told the Commons Foreign Affairs Committee that any incursion into Ukrainian territory would be unacceptable. He said: "Any crossing into Ukraine, whether small or large, would be viewed as a breach of that sovereignty, against international law and an invasion. "You can't be half-pregnant, you are either invading a country or you are not."

Hostilities have simmered for years but tensions are now escalating amid fears of a Russian invasion.

Kyiv, Ukraine – According to Washington, Russia has amassed more than 100,000 Russian soldiers on the border with Ukraine and in annexed Crimea in recent weeks.

This has stoked fears in Kyiv and the West that the Kremlin may start a new war with its neighbour and former province that chose to break away from Moscow’s political orbit.

Earlier this month, a top Ukrainian military expert told Al Jazeera that Russia could invade Ukraine as early as January, unleashing a “brief and victorious” war. But Russia denies it is planning an invasion. Moscow says it can move Russian troops wherever it wants and that any of its acts are defensive. Russian officials, including President Vladimir Putin, have for their part warned NATO against expanding eastwards. So, what is at the heart of the conflict that has been going on for more than seven years?

What is now Ukraine, Russia and neighbouring Belarus were born on the banks of the Dnieper River, almost 1,200 years ago in Kievan Rus, a medieval superpower that included a huge chunk of Eastern Europe. But Russians and Ukrainians parted ways linguistically, historically and, most importantly, politically.

Putin has, however, claimed repeatedly that Russians and Ukrainians are “one people”, part of the “Russian civilisation” that also includes neighbouring Belarus. Ukrainians reject his claims. Ukraine went through two revolutions in 2005 and 2014, both times rejecting Russia’s supremacy and seeking a path to join the European Union and NATO. Putin is particularly enraged by the prospect of NATO bases next to his borders and says Ukraine joining the US-led transatlantic alliance would mark the crossing of a red line.

US President Joe Biden has said he thinks his Russian counterpart Vladimir Putin will "move in" on Ukraine but does not want "full-blown war".

He told a news conference Mr Putin would pay a "serious and dear price" for invading, but indicated a minor incursion might be treated differently. The White House later stressed any Russian military move would be met with a swift, severe response from the West.

Russia has some 100,000 troops near the border but denies planning an invasion. President Putin has made a series of demands to the West, insisting Ukraine is never allowed to join Nato and that the defensive alliance abandons military activity in Eastern Europe.

Talks between the West and Russia have so far failed to reach a breakthrough, with some of Moscow's demands rejected as non-starters. US Secretary of State Antony Blinken is due to meet the Russian foreign minister in Geneva on Friday, having warned that Russia could attack Ukraine "on very short notice". However, at his news conference on Wednesday, Mr Biden said: "There are differences in Nato as to what countries are willing to do, depending on what happens. "If there's Russian forces crossing the border… I think that changes everything.

"What you're going to see is that Russia will be held accountable if it invades and it depends on what it does," he said. "It's one thing if it's a minor incursion, and then we end up having to fight about what to do and not do etc."

White House officials rushed to clarify the US position after Mr Biden's comments. "If any Russian military forces move across the Ukrainian border, that's a renewed invasion, and it will be met with a swift, severe, and united response from the United States and our Allies," press secretary Jen Psaki said. Hours earlier, French President Emmanuel Macron told the European Parliament that Europeans had to conduct their own dialogue with Moscow.

The exercises, involving ground troops and air forces, come amid growing instability in Afghanistan.

Chinese and Russian military forces are engaged in joint exercises in north-western China as ties grow between the two autocratic states amid uncertainty over instability in Afghanistan.

The exercises involving ground troops and air forces are due to continue through until Friday in the Ningxia Hui Autonomous region.

The region borders on Xinjiang, where China has detained more than one million Uyghurs and members of other Muslim minorities in what it calls a campaign against terrorism and extremism.

Xinjiang shares a narrow frontier with Afghanistan, and Beijing is concerned about violence spilling over its border if the Taliban take control in the country following the pullout of US and NATO troops.

While not part of a formal alliance, Russia and China have aligned their military and foreign policies largely in opposition to those of the US and its allies.

The official Xinhua News Agency said the exercises began on Monday and were presided over by Li Zuocheng, a member of the ruling Communist Party's Central Military Commission.

The exercise aims to "deepen the joint anti-terrorism operations between the Chinese and Russian militaries and demonstrate the firm determination and strength of the two countries to jointly safeguard international and regional security and stability", Xinhua said, citing Chinese and Russian officials.

"It reflects the new height of the China-Russia comprehensive strategic partnership of co-ordination for a new era and of the strategic mutual trust, pragmatic exchanges and co-ordination between the two countries," Xinhua said.

Russia has backed China in its claim to virtually the entire South China Sea, over which Beijing clashed with common rival the US at a high-level UN Security Council meeting on maritime security.