Over 39 tons of infant formula imported from Europe arrived in the U.S. over the weekend. Operation Fly Formula is aimed at relieving the formula shortage crisis and is officially underway now that the first batch has been delivered to Indiana, according to President Biden.

"Folks, I'm excited to tell you that the first flight from Operation Fly Formula is loaded up with more than 70,000 pounds of infant formula and about to land in Indiana," Biden said in a tweet. "Our team is working around the clock to get safe formula to everyone who needs it."

According to CBS News, the imported specialty infant formula is enough to fill more than half a million baby bottles. There are several more flights carrying infant formula from Europe expected to arrive this weekend.

ABC News reports that the aircraft transporting the first shipment carried two types of baby formula: Nestlé Health Science Alfamino Infant and Alfamino Junior. The second flight, arriving later this week, will be carrying Gerber Good Start Extensive HA formula.

Related: The formula shortage is leaving parents in a bind—here’s what to do if you can’t find formula

The formula was transported by military plane, White House press secretary Karine Jean-Pierre tells ABC. The plane departed from Ramstein Air Base in Germany.

After the aircraft's arrival, the baby formula was loaded into FedEx trucks and will take part in a standard quality control check that allows it to be distributed.

"We at FedEx are honored to be called on to use our network in support of this important mission with the U.S. Government," Richard W. Smith, President and CEO-elect of FedEx Express, said in a statement. "The lack of access to formula is impacting babies and families across the country, and we are proud to support the distribution of these critical items to deliver hope to those in need."

According to the most recent estimates, 43% of formula is out of stock at retailers across the country. This critical baby formula shortage has parents across the country scrambling to find the infant nutrition their babies desperately need.

Related: Viral TikTok shows the terrifying reality of the formula shortage for babies with allergies

Last week, the Food and Drug Administration (FDA) reached an agreement with Abbott Nutrition, one of the major U.S. formula manufacturers that was taken offline due to concerns about bacterial contamination, about restarting operations. The agency said that the Abbott facility could reopen in as little as two weeks, which will mean formula production could resume and be back on store shelves—but could likely still take eight weeks for production to fully reconvene. 

In a statement on Sunday, President Biden said a second Operation Fly Formula flight will transport the remaining Gerber formula to Washington Dulles International Airport. The infant formula will then be transported to a Nestlé facility in Pennsylvania and then properly distributed from there.