The White House is standing by its move to urge Americans to leave Ukraine, as Russia threatens to invade the country, maintaining that the Biden administration's decisions will "always" be in the "security interests" of individuals serving the U.S. around the globe. 

The State Department ordered the evacuation of American citizens in Ukraine on Sunday. Officials also ordered family members of employees at the United States Embassy in Kyiv to leave the country. 

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"We’re always going to make decisions that are in the security interests of people who are serving as diplomats around the world," White House press secretary Jen Psaki said Tuesday, noting that the Biden administration has "assessments" that are made by the State Department, pointing to its decision to call for Americans to leave the country, and the agency’s "Level 4" travel advisory – which Psaki says was instated in October.

The moves were intended to convey "very clearly to Americans they should leave Ukraine." 

US embassy Kyiv Ukraine

A woman walks past the U.S. Embassy in Kyiv, Ukraine, Monday, Jan. 24, 2022. (AP Photo/Efrem Lukatsky)

"Look, I will let others assess, but there are a hundred thousand troops – Russian troops – on the border of Ukraine, and no clarity that the leader of Russia doesn’t intend to invade," Psaki said. "That sounds pretty dangerous to me." 

She added that Ukrainian leaders have "welcomed" U.S. "security assistance" in the last several days.

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The State Department's travel advisory said "U.S. citizens in Ukraine should be aware that Russian military action anywhere in Ukraine would severely impact the U.S. Embassy's ability to provide consular services, including assistance to U.S. citizens in departing Ukraine."

The State Department said in the travel advisory that eligible family members are being ordered to leave the country, while U.S. citizens in Ukraine should "consider" leaving.

"On January 23, 2022, the Department of State authorized the voluntary departure of U.S. direct hire employees and ordered the departure of eligible family members from Embassy Kyiv due to the continued threat of Russian military action. U.S. citizens in Ukraine should consider departing now using commercial or other privately available transportation options," the advisory reads.

According to the travel advisory, security conditions in Ukraine can "deteriorate with little notice."

"There are reports Russia is planning significant military action against Ukraine. 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," the advisory states.

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That announcement came after the U.K.'s Foreign, Commonwealth & Development Office announced on Saturday that it had information suggesting that the Russian government is plotting to install a pro-Kremlin leader in Kyiv.

But on Monday, the Ukrainian Ministry of Foreign Affairs accused the United States of "excessive caution" for ordering family members of Kyiv Embassy staff to leave the country, as Russia gets closer to invading Ukraine by the day.

Press secretary Jen Psaki

Press secretary Jen Psaki speaks at a press briefing at the White House in Washington, Tuesday, Jan. 25, 2022. (AP Photo/Andrew Harnik)

"We have taken note of @StateDept’s decision re departure of family members of @USEmbassyKyiv staff," Ukraine spokesman Oleg Nikolenko tweeted. "While we respect right of foreign nations to ensure safety & security of their diplomatic missions, we believe such a step to be a premature one & an instance of excessive caution."

The United Kingdom is also bringing home "Some Embassy staff and dependents" due to the "growing threat from Russia." 

Meanwhile, President Biden is weighing whether to deploy thousands of U.S. troops to Eastern Europe to bolster a broader NATO effort to protect allied countries bordering Russia and Ukraine. 

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Defense Secretary Lloyd Austin, on Monday, put 8,500 U.S. troops on heightened preparedness in case of a decision to deploy. 

Ukraine's territory has long been in Putin's crosshairs, especially amid recent NATO considerations of potentially allowing Ukraine to join the alliance. It is one of several post-Soviet republics in the region that shifted toward an alliance with the West after the collapse of the Soviet Union. 

Putin was in the Soviet KGB for many years before beginning his political career, and has said the collapse of the Soviet Union was the "greatest geopolitical catastrophe" of the 20th century. 

Putin also stresses Russian ethnic and cultural influences in Ukraine as reasons why it should be part of Russia. That was a significant part of the justification Russia used when it illegally annexed the Crimea region of Ukraine in 2014. 

President Biden has warned there would be consequences for Russia if it invades Ukraine. But he also last week appeared to say that the U.S. might not respond forcefully to a "minor incursion" by Russia. That statement tipped off a wave of outrage both inside and outside the United States, followed by an effort by the White House to clean up the president's comments. 

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"I've been absolutely clear with President Putin. He has no misunderstanding, if any, any assembled Russian units move across the Ukrainian border, that is an invasion," Biden said, adding that this would "be met with severe and coordinated economic response that I've discussed in detail with our allies, as well as laid out very clearly for President Putin."

While NATO and the United States are fortifying allies, including the Baltics, it is not likely the western alliance will send troops into Ukraine itself, where they would be at risk of a potentially major military engagement with Russia. 

Biden administration officials told Fox News on Tuesday that they are also preparing "severe" sanctions against Russia should they invade Ukraine, which would have an "immediate and visible effect on the day they are implemented." 

"That means the gradualism of the past is out, and this time, we will start at the top of the escalation ladder and stay there," a senior administration official said. "We've made efforts to signal this intention very clearly, and I would say, a deepening selloff in Russian markets, its borrowing costs, the value of its currency market, imply default risk, reflect the severity of the economy consequences we can and will impose on the Russian economy in the event of a further invasion." 

Fox News' Lucas Tomlinson, Jennifer Griffin, Tyler Olson, and The Associated Press contributed to this report.