Ukrainian President Volodymyr Zelenskyy laid some blame for deaths in his country on Western nations not imposing a no-fly zone over Ukraine. 

"Thirteen days, during which we've been just hearing promises, when they tell us that yes, very, very soon you'll get help in the sky, there’ll be planes given to us," Zelenskyy said during a speech Tuesday. 

RUSSIA INVADES UKRAINE: LIVE UPDATES

"The fault lies with the invaders," Zelenskyy added. "But the responsibility for this lies also with those who have not been able to make an obviously necessary decision somewhere in the West, somewhere in the offices for 13 days. Those who have not yet secured the Ukrainian sky from Russian murderers. Those who did not save our cities from airstrikes, from these bombs, missiles, although they can."

Volodymyr Zelenskyy

In this photo, Feb. 27, 2022, taken from video provided by the Ukrainian Presidential Press Office, Ukrainian President Volodymyr Zelenskyy speaks to the nation in Kyiv, Ukraine.  Russian state media is spreading false claims that Ukrainian President Volodymyr Zelenskyy has fled Kyiv in what experts say is an effort to discourage Ukrainians and erode support for Ukraine around the globe.  (Ukrainian Presidential Press Office via AP, File) (Ukrainian Presidential Press Office via AP, File)

Zelenskyy has implored world leaders to impose a no-fly zone over his country, including to President Biden, NATO and to more than 280 U.S. lawmakers. But the issue of imposing a no-fly zone is far more complicated than just prohibiting aircraft over Ukraine, according to U.S. and world leaders. 

WHAT WOULD HAPPEN IF THE US IMPOSED A NO-FLY ZONE IN UKRAINE?

"The only way to implement a no-fly zone is to send NATO fighter planes into Ukrainian airspace, and then impose that no-fly zone by shooting down Russian planes," NATO Secretary-General Jens Stoltenberg said. "We understand the desperation, but we also believe that if we did that, we would end up with something that could end in a full-fledged war in Europe." 

NATO Secretary Jens Stoltenberg took questions from reporters Friday, March 4, 2022.

NATO Secretary Jens Stoltenberg took questions from reporters Friday, March 4, 2022. (NATO)

A no-fly zone risks a direct military conflict with Russia, which could potentially escalate to a third world war, pitting nuclear power countries such as the U.S., France and the U.K. against fellow nuclear power Russia

10-YEAR-OLD UKRAINIAN GIRL SHOT AND KILLED BY 'DRUNK RUSSIAN SOLDIERS,' FAMILY SAYS

"If people understand what it means, it means World War III. It means starting World War III," Republican Florida Sen. Marco Rubio said Saturday on ABC's "This Week." "It's not some rule you pass that everybody has to oblige by. It's the willingness to shoot down the aircrafts of the Russian Federation, which is basically the beginning of World War III."

CLICK HERE TO GET THE FOX NEWS APP

Russia first invaded Ukraine on Feb. 24, and the two nations have been battling since. The UN estimates that about 2 million Ukrainians have fled the nation to neighboring countries. 

Biden is slated to announce actions Tuesday morning that will continue holding Russia accountable for the war, including an expected ban on Russian oil imports to the U.S.