Fears that Russia could invade Ukraine grew more concrete on Friday as the US issued a warning that such an attack could conceivably come within the next 10 days, while Western governments urged their citizens to get out of Ukraine.
Speaking to reporters after US President Joe Biden conducted a videoconference with multiple world leaders, US National Security Advisor Jake Sullivan said there are new concerns that the long-feared attack could start before the Winter Olympics end on February 20.
Until now, most speculation of any such attack had leaned towards an invasion starting after the Olympics, so as not to rile Beijing. But Sullivan cautioned that there is no certainty that an attack has been ordered.
"The fastest way to end this would be for Russia to de-escalate its forces," he said.
Concerns have been growing for months now that Russia - which has been building up its forces at the Ukrainian border - is contemplating an invasion of Ukraine. Russian-backed forces already control parts of eastern Ukraine and Russia annexed the Crimean Peninsula from Ukraine in 2014.
Russia has denied that any such plans are afoot. But it has also used the attention on the region to express fears that NATO has encroached too close to its territory and demanded that the security alliance withdraw from what Russia considers its area of influence.
Against this backdrop, Britain, the Netherlands and the US urged citizens to get out of Ukraine. Sullivan recommended any Americans still in Ukraine do so within the next "24 to 48 hours." British nationals were told to leave "while commercial means are still available."
In light of the perceived threat, NATO is planning to increase its troop presence in its eastern flank close to Ukraine, despite demands from Moscow to do precisely the opposite.
The 30 alliance members signed off a related proposal this week, after weeks of discussion.
More NATO troops
Following Moscow's 2014 Crimean annexation, NATO deployed four battle groups of multinational forces in Estonia, Lithuania, Latvia and Poland.
With more than 100,000 Russian troops now stationed near Ukraine's borders and fears over an invasion mounting, plans are afoot to station more NATO troops nearby in states like Romania.
The decision is to be confirmed and announced at a NATO defence ministers meeting in Brussels next week, and could be implemented within weeks.
But the build-up by NATO forces was already under way on Friday. Spain deployed four fighter jets to Bulgaria, along with 130 troops who had already arrived, part of an operation to strengthen aerial surveillance.
Separately, around 700 US military vehicles will travel through the Czech Republic starting next week, the Czech Defence Ministry said on Friday, part of the Saber Strike 2022 military exercises.
And six advanced artillery systems will be sent to Lithuania on Monday to strengthen a German-led NATO battalion in the country, the Defence Ministry in Berlin said.
Slovakia and Bulgaria could also possibly host NATO troops. France has already offered to lead a NATO battle group in Romania. "Many other allies" are willing to contribute, NATO Chief Jens Stoltenberg said Friday.
Large-scale military exercise
Estonia, Latvia and Lithuania also demanded more information from Belarus about its large-scale joint military manoeuvre with Russia, now in its second of 10 days.
They want details of the exercise under Chapter III of the Vienna Document of the Organization for Security and Co-operation in Europe (OSCE). The convention regulates how OSCE states must exchange information on each other's military activities.
Russia says NATO's concerns are unfounded, but stressed that its continued presence in Eastern Europe could stoke tensions. The Kremlin has accused NATO countries of scare-mongering and ignoring promises it made about keeping forces out of the Eastern Europe.
It says the only way to calm the situation is for the West to agree to its wish list of security demands issued in December.
US Secretary of State Antony Blinken warned on Friday that Russian troops could invade Ukraine "at any time."
"We're in a window when an invasion could begin at any time and to be clear: That includes during the Olympics," Blinken said in Melbourne, Australia, following a meeting of foreign ministers from Australia, Japan and India.
Russian President Vladimir Putin had attended the opening of the Winter Olympics in Beijing on February 4, together with China's leader Xi Jinping. The Games are due to run until February 20.
"Simply put, we continue to see very worrying signs of Russian escalation," Blinken said.