Fears of a Russian military attack on neighbouring Ukraine are growing amongst the international community, as the Kremlin continues its build-up of troops on the border.
Ukraine has reached out to the international community for help after watching Russia's military presence steadily grow on its doorstep.
NATO has called for the Kremlin to be transparent with its ambitions while the US has publicly announced its commitment to Ukraine's security and sovereignty.
However, Russia has said it does not want to raise tensions in the region and only wishes to protect itself against threats from the West.
Here is a quick guide to what is happening at Ukraine's border with Russia and why world leaders fear conflict.
Tensions have been high between Russia and Ukraine for several years
Tensions between the neighbouring nations have been on and off for many years.
Recently, Ukraine has allied itself more with the West, while keeping its distance from Moscow.
A war in 2014, which led to the annexation of Crimea from Ukraine to Russia has led to poor relations between both countries.
Russia's President Vladimir Putin declared Crimea was rightfully part of Russia, which is still not accepted by Ukraine.
"Our country has regained its historical unity," he said during a speech in Crimea earlier this month.
"They [Crimea] are with Russia forever now, as that is the sovereign, free and unbending will of the people, of all our people."
Russia has also backed separatist movements in Ukraine's east, which led to a six-year civil war.
Rebel forces control eastern Ukraine regions including Donetsk and Luhansk, which went to war against the Ukraine government in the wake of massive protests in February of 2014.
This war has forced Ukraine to strengthen its political relations with the west, further dividing Kyiv and Moscow.
Russia has been building its military presence on the border over several months
Russia has been steadily building up its presence along the border with Ukraine over the past year.
There are estimates of around 100,000 Russian troops are either near the border or based in eastern Ukraine, in regions controlled by separatist rebels.
In September, Russia held war games with Belarus and a handful of other nations near the Ukraine border.
The war games, which Russia said involved more than 200,000 personnel, was a culmination of a larger three-month military exercise.
But once the war games finished many Russian troops remained near the border according to Ukraine.
The Ukrainian Defence Ministry claimed that about 90,000 to 100,000 Russian troops are stationed in the Russian town of Yelnya, a town about 260 kilometres north of the Ukrainian border.
The commander-in-chief of the Ukrainian armed forces, Lieutenant General Valeriy Zaluzhny, said Russia has about 2,100 military personnel in the east of the country which is controlled by separatist rebels.
It is a military build-up that was described as "unusual" by NATO Secretary-General Jens Stoltenberg.
"What we see is a significant, large Russian military build-up," he said.
"We see an unusual concentration of troops."
Why have tensions risen in recent days?
Tensions have simmered since the military build-up started earlier in the year, but have increased over the past fortnight.
Russia was on high alert when two US warships, USS Mount Whitney and USS Porter, sailed into the Black Sea earlier in November.
Tensions escalated last Wednesday when US Secretary of State Antony Blinken met his Ukrainian counterpart Dmytro Kuleba in Washington DC.
During a joint press conference, the US declared its "grave concern" over Russia's military presence and said its commitment to Ukraine's security and territorial integrity was "ironclad".
Mr Blinken said the US did not know Russia's intentions but said Moscow's "playbook" has been in the past to invent provocations along its border to justify military intervention.
"We don't have clarity into Moscow's intentions, but we do know its playbook," he said.
"If there are any provocations that we're seeing, they're coming from Russia."
This drew an immediate response from the Kremlin which denied Russia wanted to invade Ukraine.
"Never planned, never did, and never going to do it unless we're provoked by Ukraine, or by somebody else," Russia's deputy UN ambassador Dmitry Polyansky said.
However, Mr Kuleba sought backing from NATO on Monday during meetings in Brussels, despite Ukraine not being a member of the alliance.
In a joint statement, the foreign ministers of Germany and France warned Russia against taking any military action in Ukraine.
"Against the backdrop of renewed concerns about Russian movements of troops and hardware near Ukraine, we call on Russia to adopt a posture of restraint and provide transparent information about its military activities. Any new attempt to undermine Ukraine's territorial integrity would have serious consequences," the ministers said.
What is Russia's reasoning for increasing its military presence on the Ukraine border?
While the West is worried about conflict on the border, the Kremlin says Russia is protecting itself from threats made against it.
The conflict for Russia revolves around the US warships sailing into the Black Sea, which Russia sees as a threat to its border.
Russia earlier in the year said it fired a warning shot at a British warship, something the UK government denied.
Many countries are connected to the Black Sea by coastlines including Ukraine and Russia.
However, Russia significantly increased the amount of territorial claim it had to the Black Sea when it annexed Crimea from Ukraine in 2014.
The move was condemned by Europe and the US, who still recognise the peninsula as the rightful territory of Ukraine.
"There are a lot of threats coming from Ukraine," Mr Polyansky told reporters at the UN headquarters last Thursday.
"And don't forget that the American warships around the Black Sea acting very close."
"So, every day is a very difficult day to avoid a direct clash in the Black Sea. We warned our American colleagues that this is a real provocation."
A day later, the Russian Defence Ministry echoed the same concerns, stating Russia was worried the US was helping Ukraine retake control of its eastern regions held by rebels.
"The real goal behind the US activities in the Black Sea region is exploring the theatre of operations in case of Kyiv's attempts to settle the conflict in the south-east by force," the ministry said in a statement.
Why is Europe and the US worried?
Ukraine has become an ally to the West since it split from the former Soviet Union, turning its back on Moscow.
However, Russia is a supporter of separatists in the east of Ukraine.
The major worry for the West is another war similar to 2014 when Russia increases its territorial claim.
Mr Blinken said the current accumulation of troops on the border is reminiscent of Russia's forced annexation of Crimea.
"We do know that we've seen in the past: Russia mass forces on Ukraine's borders, claim some kind of provocation by Ukraine, and then invade. That's what they did in 2014," he said.
It was a fear shared by NATO's Secretary-General who said: "We know that Russia has been willing to use these types of military capabilities before to conduct aggressive actions against Ukraine."
Putin accuses UK of 'provocation'
The Russian leader uses his annual call with voters to explain last week's tense encounter with a British warship off Crimea, and to accuse the US of being involved.
"I think it's important also that we don't now increase tensions, but we have to be clear-eyed, we need to be realistic about the challenges we face," Mr Stoltenberg said.
France's Foreign Ministry said Russia was "clearly warned of the serious consequences of any further possible damage to the territorial integrity of Ukraine".
The tensions could lead to more fighting in eastern Ukraine which has claimed many lives.
The international community was dragged into the conflict when Malaysian Airlines Flight 17 was shot down, killing 298 people.
MH17 was flying from Amsterdam to Kuala Lumpur when it was shot down by a missile fired from territory held by pro-Russian rebels during fighting in eastern Ukraine, international investigators said.
Dutch-led investigators, supported by many nations including Australia, blamed Russia for the missile attack.
Russia has said it does not want to fight but has left the door open for military conflict on the Ukraine border.
"If you read the threats that are being pronounced in Ukraine against Russia, against Russian territorial integrity, then you will understand that a certain precaution is a logical step in such a situation," Mr Polyansky said last week.
Posted 1h ago1 hours agoTue 16 Nov 2021 at 7:00amShareCopy linkFacebookTwitterArticle share optionsShare this onFacebookTwitterLinkedInSend this byEmailMessengerCopy linkWhatsApp