The U.S. Embassy in Moscow is advising American citizens to consider leaving Russia immediately as more commercial flights from the country are being canceled.

The U.S. Embassy in Moscow said in a statement late Sunday that citizens should leave while commercial options are still available amid the ongoing Russian invasion of Ukraine and rising tensions between the West and Russia, Bloomberg reported.

In January, the U.S. State Department issued a recommendation that Americans should avoid traveling to Russia.

According to DW News, Russian carrier Aeroflot said it was cutting off flights to all European destinations, adding that fellow Russian carrier Rossiya Airlines would also be affected.

The Russian carrier said Aeroflot cancels and suspends flights from Moscow and St. Petersburg to a number of destinations due to the closure of the airspace of several European countries.

Some European countries have imposed a ban on Russian aircraft from their airspace, including Germany, Italy, Iceland, the Netherlands, the U.K., and most Eastern European EU member states.

Russia's President Vladimir Putin has ordered that Russia's nuclear deterrence forces be put on high alert. Putin said that he ordered the defense minister and the chief of the general staff of the Russian armed forces to put the deterrence force of the Russian army into a special mode of combat service.

The United Nations high commissioner for refugees, Filippo Grandi, said the number of people who have fled Ukraine has now surpassed 368,000.

READ NEXT: Pres. Joe Biden's Administration Handed China Intelligence on Russia's Invasion; China Told Russia the U.S. Intel: Report

U.S. Embassy in Moscow Calls Amid Russia-Ukraine Crisis

The U.S. Embassy in Moscow also asked American citizens to have a "contingency plan that does not rely on U.S. government assistance," Reuters reported.

The embassy advised Americans on February 20 to have an evacuation plan with the threat of attacks in Moscow and along the Russian border with Ukraine.

The E.U.'s foreign policy chief, Josep Borrell, said the Russia-Ukraine crisis would be a defining moment for the history of Europe.

Borrell noted that there had been a "taboo" against the European Union using collective resources to arm a country that is at war with another. However, he added that "another taboo has fallen these days," NBC News reported.

Sergiy Kyslytsya, Ukraine's ambassador to the United Nations, said that Putin has "resorted to nuclear blackmail" and perverted the basis of the international Genocide Convention for his own agenda.

Russia's Ambassador to U.N. Denies Targeting Civilians in Ukraine

Vasily Nebenzya, the Russian diplomat assigned to the U.N., denied accusations of Russian armed forces targeting Ukrainian civilians.

Nebenzya continued to push the narrative that crimes by Ukrainian nationalists were what drove Putin's invasion.

Earlier this month, President Joe Biden called on American citizens in Ukraine to leave "now" as Russia continues to threaten an invasion. 

Biden told NBC News anchor Lester Holt that it was not like dealing with a terrorist organization but "with one of the largest armies in the world."

"It's a very different situation, and things could go crazy quickly," the president added.

READ MORE: Pres. Joe Biden Smirks, Picks Teeth After Reporter Asks if He 'Underestimated' Russia's President Vladimir Putin 

This article is owned by Latin Post.

Written by: Mary Webber

WATCH: Thousands of Ukrainian, US Citizens Flee Amid Russia's Initial Invasion | Nightline - From ABC News