"Fox & Friends" co-host Brian Kilmeade pressed a White House spokesperson on the military's vaccine mandate, as thousands face being discharged over the shot while branches struggle to meet recruitment goals. 

National Security Council Coordinator John Kirby discussed Tuesday the need for the requirement, arguing the vaccine is a necessity used to enhance military readiness. 

"Vaccinations are a valid military requirement," Kirby said on "Fox & Friends" on Tuesday. "You want your troops to be ready, and part of being ready is being healthy and not being able or not having the ability to infect your unit and to make their unit readiness any worse than it is."

MILITARY RECRUITMENT LAGS DESPITE REDUCED TARGETS, RECORD INCENTIVES TO BOOST INVESTMENT

Kilmeade pushed back on Kirby's remarks, questioning the vaccine's efficacy with regard to newer COVID variants. 

U.S. Military Members Receive COVID-19 Vaccinations At Fort Knox

FORT KNOX, KY - SEPTEMBER 09: Soldiers file paperwork before being administered their COVID-19 vaccinations by Army Preventative Medical Services on September 9, 2021 in Fort Knox, Kentucky. (Photo by Jon Cherry/Getty Images) ((Photo by Jon Cherry/Getty Images))

"We all know that this vaccine does not address any of the variants we're currently experiencing," Kilmeade said. "So, therefore, there's minimal positive to getting it now, which is why you guys don't even talk about it. To invest in our people and train them and then dismiss them for an experimental vaccine is folly."

Kilmeade asked Kirby if it was worth losing 20,000 service members to the mandate, as a majority of branches struggle to meet recruitment goals. 

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"Brian, we would rather not lose anybody, of course, to the vaccine," Kirby said. "We'd rather not lose anybody from a retention perspective, to have them leave the service earlier than they wanted, or we wanted them to, but it's a valid military requirement."

"No, it is not," Kilmeade insisted. "This is an experimental vaccine that just came off the shelf. You know it's not valid, and… it's [a] risk our national security. Admiral, you are a military officer. You could talk sense into this White House."

Nearly 20,000 service members face discharge over the mandate, even as Biden declared the pandemic "is over."