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WASHINGTON — The Pentagon's top general said Monday that he could not yet answer the fundamental questions about why four American soldiers died Oct. 4 after an ambush in a remote village in the African nation of Niger.

Three weeks after the attack by what he said was an ISIS affiliate, Marine Corps Gen. Joseph Dunford, the chairman of the Joint Chiefs of Staff, said several matters remain under investigation. They include whether the U.S. had adequate intelligence and equipment for its operation, whether there a planning failure, whether the mission changed and why it took so long to recover one of the bodies.

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"We owe you more information; more importantly, we owe the families of the fallen more information," Dunford said. "Did the mission change? It's a fair question."

Dunford said the four soldiers died after a battle that started on Oct. 4 in a "complex situation," leading to a "difficult firefight." At a Pentagon news conference, he took every question reporters had, butcould not provide answers to many of them.

A group of 12 American soldiers accompanied 30 Nigerien forces to an area north of the capital on Oct. 3, and then spent much of the night on a reconnaissance mission, he said. The next morning, they were attacked by about 50 enemy fighters traveling by vehicle, carrying small arms and rocket-propelled-grenade launchers.

The team fought for an hour before calling for help, Dunford said, adding that the soldiers may have thought they could handle the attack.

Within minutes, a U.S. drone was flying above, but it took another hour for French jets to arrive and still longer for helicopters to ferry wounded Americans to safety. The bodies of three Americans killed in the fighting were transported out of the battle scene, but one — Sgt. La David Johnson — wasn't recovered until Oct. 6.

The Niger mission, and a clash between Sgt. Johnson's family and the Trump administration, have together become a major political issue, with members of Congress demanding more information.

Dunford defended the broader American mission in Niger. He said U.S. forces have been in the country intermittently for more than two decades. Currently, some 800 U.S. service members are supporting a French-led mission to defeat ISIS, al-Qaida and Boko Haram in West Africa.