Retired Gen. Jack Keane, chairman of the Institute for the Study of War, told Fox News on Thursday that President Biden is wrong when he claims there is no "mission accomplished" sentiment as the White House continues to further accelerate military withdrawal from Afghanistan after nearly 20 years.

Biden was asked whether there is a "mission accomplished" moment to be felt with the pullout of troops, and the president answered in the negative. Keane disagreed.

"Of course there's a mission accomplished," he told "The Story" host Trace Gallagher. 

"We stopped the to-date 20 years of sacrifice by American troops and civilians that supported them there, have prevented another attack like 9/11. That's what we went there to do and we have accomplished that mission," Keane added.

"I maintain the threat is still there, and we have more to do. Our troops should feel very good about the sacrifices that they made, and their families have contributed in terms of the sacrifice."

Keane also reacted to Biden speaking Thursday about how he does not want to send "another generation" to a war that has "no reasonable expectation of achieving a different outcome" than the one at present. The president reportedly added that the Taliban is not strong enough at this point to retake Afghanistan as it had prior to U.S. and NATO involvement.

The Fox News contributor suggested Biden appeared to be half-right.

"Frankly I disagree with that," Keane said. "Here's why. The president is right. We have not been fighting on the ground in Afghanistan since 2014 when we ended combat operations. What have we been doing? Very robustly we have been providing an intelligence capability to the same forces he referenced, the 300,000.

"But here's the kicker. We have been providing decisive air power. [The Afghans are] the ground force and we're providing the air power to stop the Taliban."

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Keane said Biden has essentially misjudged that. By removing all troops, including air support for Afghan militia, he takes away the major defense against the Taliban retaking Kabul or worse. Without proper air power, the infantries may soon not be able to withstand Taliban insurgence.

"The Taliban will begin to mass at some point to take down the major cities in Afghanistan. They're holding back now until the United States is all gone. Then we'll see that. That is when air power would be incredibly effective and decisive to be able to stop that," the former Vice Chief of Staff of the United States Army added.

On May 1, 2003, former President George W. Bush famously announced "Mission Accomplished," replete with a celebratory banner, on the Iraq War.

The Texas Republican declared that "the United States and our allies have prevailed" in a speech aboard the U.S.S. Abraham Lincoln. However, that was mocked by critics because the conflict itself continued for several more years.