"After speaking with U.S., Ukrainian, and foreign leaders working to support Ukraine at the Munich Security Conference last month, we believe the U.S. needs to take a hard look at providing F-16 aircraft to Ukraine," senators wrote in the letter, which was spearheaded by Sen. Mark Kelly, D-Ariz.

"This would be a significant capability that could prove to be a game changer on the battlefield."

The letter noted that two Ukrainian pilots recently traveled to Tucson, Arizona, to take part in a skills assessment on an F-16 simulator at Morris Air National Guard Base. The senators called it a "critical step" in gauging Ukrainian forces' capabilities to receive western fighter jets. Ukraine's military mostly flies Soviet-made aircraft such as the MiG-29.

UKRAINE WAS THE 3RD-LARGEST IMPORTER OF ARMS IN 2022, THANKS TO AID FROM US, EUROPE

A bipartisan group of lawmakers in the House sent a similar letter to Biden last month urging him to provide Ukraine with aircraft. 

"F-16s or similar fourth generation fighter aircraft would provide Ukraine with a highly mobile platform from which to target Russian air-to-air missiles and drones, to protect Ukrainian ground forces as they engage Russian troops, as well as to engage Russian fighters for contested air superiority," the lawmakers wrote on Feb. 28. 

Polish Prime Minister Mateusz Morawiecki said Tuesday that his government could send Soviet-made MiG-29 fighter jets to Ukraine "within the next four to six weeks," according to the Associated Press. Other European allies have also hinted that they are open to providing Ukraine with military aircraft. 

It would not be the first time that the U.S. reverse course on sending certain types of military equipment to Ukraine. The U.S. held out on sending Abrams M1 tanks for several months before the Pentagon announced in January that it would send 31 tanks to the battlefield.