"America’s Newsroom" hosts Bill Hemmer and Dana Perino pressed Pentagon press secretary John Kirby Wednesday on why American citizens were left in Afghanistan and why the intelligence data on evacuees was incorrect. 

"Why was that so hard to nail down?" Perino asked, referring to the number of Americans still in Afghanistan when the withdrawal was completed. 

Kirby called the Pentagon’s knowledge of the number of Americans stuck in the Taliban-ruled country "a bit of a moving target," citing dual-nationalism and the difficulty of gathering information on whether the citizens wanted to leave as primary hurdles in accurately assessing who was still trapped. 

"What I think is encouraging though is that now almost 1,000, since August 31, since we left, have been brought out, and we’re continuing to look for others that want to go," said Kirby.

PSAKI GRILLED ON AMERICAN CITIZENS STILL LEFT IN AFGHANISTAN

"The problem with the numbers is that you were off by 90%," Hemmer responded.

Pentagon spokesman John Kirby speaks during a media briefing at the Pentagon, Wednesday, Oct. 27, 2021.

Pentagon spokesman John Kirby speaks during a media briefing at the Pentagon, Wednesday, Oct. 27, 2021. (AP Photo/Alex Brandon)

"Well again it’s not a science, Bill. It’s not like they register on some sort of list that we have that just static and permanent" replied Kirby, as Hemmer interjected. 

The "America’s Newsroom" host asked if the Pentagon had merely assumed that remaining Americans crossed into Pakistan. 

Kirby said that "there were lots of assumptions," including the assumption that Americans crossed into Pakistan or that they feared declaring an urge to leave. 

A source familiar with the matter told Fox News that previous estimates of U.S. citizens still residing in Afghanistan grew because not everyone who was eligible to leave had registered with the embassy. In many cases, people wanted to stay because of family or deep cultural roots but later changed their minds.

Evacuees wait to board a Boeing C-17 Globemaster III during an evacuation at Hamid Karzai International Airport, Kabul, Afghanistan, Aug. 23, 2021.

Evacuees wait to board a Boeing C-17 Globemaster III during an evacuation at Hamid Karzai International Airport, Kabul, Afghanistan, Aug. 23, 2021. (U.S. Marine Corps photo by Sgt. Isaiah Campbell)

The Pentagon press secretary also asserted that he didn’t think it was a "bad thing" that the number of Americans left in Afghanistan increased.

"As we have proven successful at getting more out, more and more are now becoming comfortable saying, ‘Hey we want to go to.’ So, again we don’t think it’s a bad thing that the numbers increased. We think it’s a good thing, and we’re going to continue at this. Even though our military mission's over, the mission to help Americans leave Afghanistan is not," he added. 

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The State Department has said it is "in touch" with the remaining U.S. citizens who want to leave Afghanistan, are prepared to depart, and have the necessary travel documents.

Fox News' Timothy Nerozzi contributed to this report.