The U.S. on Tuesday warned it believes Russia is "stepping up efforts" to launch missile strikes on Ukraine as its Independence Day nears.

"The Department of State has information that Russia is stepping up efforts to launch strikes against Ukraine’s civilian infrastructure and government facilities in the coming days," the U.S. Embassy in Ukraine alerted.

The six-month anniversary of Russia’s invasion of Ukraine on Feb. 24 coincides with Ukraine’s Independence Day Wednesday and officials are worried Russia will use the moment increase its aggression beyond the frontlines. 

Building in Donetsk in Ukraine damaged by shelling

A view of the Donetsk People's Republic administration building damaged by shelling in Donetsk, separatist Donetsk People's Republic, eastern Ukraine, Tuesday Aug. 23, 2022. (AP Photo/Alexei Alexandrov)

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"Russian strikes in Ukraine pose a continued threat to civilians and civilian infrastructure," the embassy said, urging all U.S. citizens to leave Ukraine immediately using private transportation methods.

The announcement – the first of its kind in recent months – comes one day after Kyiv banned Independence Day celebrations in the capital city over concerns Russia could target the mass gatherings. 

Wednesday will mark 31 years since Ukraine left the Soviet Union, but there will be no public celebrations as Kyiv placed a ban on mass gatherings and reissued remainders to listen to air-raid sirens amid the heightened threat.

Volodymyr Zelensky behind Ukraine flag

 In this photo provided by the Ukrainian Presidential Press Office on July 8, 2022, Ukrainian President Volodymyr Zelenskyy, attends a meeting with military officials during his visit the war-hit Dnipropetrovsk region.  (Ukrainian Presidential Press Office via AP, File)

Ukrainian President Volodymyr Zelenskyy on Tuesday vowed a "powerful response" if Russia does increase its intensity of attacks over the next two days. 

But over the weekend he warned, "We should be aware that this week Russia may try to do something particularly nasty, something particularly cruel."

Former intelligence officer in Russian doctrine and strategy for the Defense Intelligence Agency (DIA), Rebekah Koffler, echoed these concerns and told Fox News Digital that Russia blames Kyiv for the car bombing that killed the daughter of a top Putin ally and the recent attacks in Crimea.

"Russia almost certainly is planning to escalate assault operations on Ukraine," Koffler said. "The Russians believe Ukraine is responsible for these attacks. 

"Putin will likely use these events as justification for ratcheting up bombardment of Ukraine, possibly the capital Kyiv," she warned. 

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Russia has long relied on heavy artillery and missile fire to attack civilian and military targets throughout its invasion. 

On Tuesday Zelenskyy said that while nearly 3,500 cruise missiles had struck Ukrainian targets, it is "simply impossible" to count the number of artillery strikes the Russian forces have rained down on Ukraine.

Ukraine war Russia

KYIV, UKRAINE - MARCH 23: The site of a rocket explosion where a shopping mall used to be on March 23, 2022 in Kyiv, Ukraine.  (Photo by Anastasia Vlasova/Getty Images)

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"There are too many of them, they are too intense," he added. 

Officials across Ukraine have implemented curfews and in Ukraine’s southern Mykolaiv region residents have been urged to work from home through Wednesday.