The U.S. State Department issued a travel advisory early Saturday morning, announcing that the American Embassy in Kyiv had been evacuated amid the threat of Russian invasion.

"On February 12, 2022, the Department of State ordered the departure of most U.S. direct hire employees from Embassy Kyiv due to the continued threat of Russian military action," the travel advisory read.

The level four advisory also urged U.S. citizens not to travel to the area and those who remain in the country to depart "immediately."

The State Department added that on Sunday, the embassy in Kyiv will halt all consular services and will "maintain a small consular presence in Lviv, Ukraine to handle emergencies, but will not be able to provide passport, visa or routine consular services."

A senior State Department official said that some staff would be staying in Kyiv, while others would be relocated to Lviv, but they declined to provide numbers on how many would be at each. 

The official explained that one reason some employees had been moved to Lviv, which is situated in the western region of Ukraine, was "its closer proximity to U.S. diplomatic and consular facilities in neighboring countries," so officials could closely coordinate with colleagues nearby and move out people safely if needed should Russia engage in military action. 

The official said that "a couple thousand Americans" had told the U.S. in recent days that they were in the country and that officials had been in touch with them regarding whether they intend to leave.

The official noted it was difficult for officials to know at any given time how many Americans were in any country, including Ukraine, but said that of the several thousand who had been in touch, some had already left.

The official underscored that war is becoming an increasingly likely scenario. 

"It appears increasingly likely that this is where ... this situation is headed, toward some kind of active conflict," the senior State Department official said, noting that it was "past time" for private citizens to leave the country.

The official said that they were not engaged in organizing departures for Americans, noting people have had "ample opportunities" to exit the country. 

The official added that "very few of the American citizens who have been in touch with us in recent days have expressed an inability to physically get themselves out of the country."

The news is the latest development in what appears to be an increasingly volatile situation in the former Soviet state. 

The Russian military has amassed hundreds of thousands of troops at its border with Ukraine, a posture that has not shifted much in weeks amid efforts by the U.S., Canada, U.K. and other Western allies to solve the escalating situation diplomatically. 

Russia has demanded that NATO refuse to allow Ukraine and other former Soviet states into its alliance, a demand that the organization has rebuffed. 

White House national security adviser Jake Sullivan sounded the alarm Friday afternoon, warning that a Russian invasion of Ukraine could take place "any day now," and Secretary of State Antony Blinken sounded a similar tone, stating that "we’re in a window where an invasion could begin anytime."

News of a potential Russian incursion comes amid the 2022 Winter Olympic Games, a second time when the world's athletes have traveled to Beijing specifically to compete. 

“This marks the second time that Russia has escalated aggression toward a sovereign country during a Beijing Olympics,” Daniel Kritenbrink, assistant secretary of State for East Asian and Pacific affairs, said in a media briefing earlier this month. 

The Biden administration, including President Biden himself, has warned that Americans should evacuate the country voluntarily amid the threat of Russian aggression.

In its advisory Saturday, the State Department reiterated the dangers of war between Ukraine and its neighbor. 

"There are continued reports of a Russian military build-up on the border with Ukraine, indicating potential for significant military action against Ukraine," it stated.

"The security conditions, particularly along Ukraine’s borders, in Russia-occupied Crimea, and in Russia-controlled eastern Ukraine, are unpredictable and can deteriorate with little notice," it added.  

However, it remains unclear if Russian President Vladimir Putin will certainly give the order to invade, and some experts remain skeptical of a full-scale attack. 

Biden is slated to speak with Putin on Saturday about the developing situation.

The U.S. as well as its allies have warned of crushing economic sanctions on Russia if it chooses to invade Ukraine. 

Updated 10:11 a.m.