The attackers who ambushed and killed four U.S. soldiers in Niger had “no real ties” to the Islamic State group, the SITE Intelligence Group said Friday.

The company, which tracks terror groups, said the leader of the jihadist extremists in West Africa, Adnan Abu Waleed al-Sahrawi, had pledged allegiance to ISIS in 2015 but never followed through with any coordination, which may explain why ISIS has not claimed responsibility for the attack.

After Sahrawi’s 2015 pledge, there were no communiques, media releases, or further acknowledgment of the relationship, and a letter by the leader to followers in May made no mention of ISIS or its war in Iraq and Syria, Rita Katz, director of SITE, wrote on the group’s website.

“To call Sahrawi an ISIS operative would be inaccurate, as he has clearly left behind his ties to the group,” she wrote. “But as this tragic killing of U.S. soldiers has appeared to show, he nonetheless exerts a dangerous amount of power in the region.”

Katz said the military currently believes the attack was carried out by the Islamic State in the Greater Sahara.

Gen. Joseph Dunford, chairman of the Joint Chiefs of Staff, said this week that an "ISIS-affiliated group" appeared to be responsible.

"I think what you bring up is what we're dealing with in many places, is ISIS and al Qaeda — ISIS in this case — they try to leverage local insurgencies and connect those local insurgencies globally," Dunford said. "This is the challenge that we're dealing with. And so, our initial assessment is these are local tribal fighters that are associated with ISIS.”

U.S. Africa Command is still investigating the incident, which included a two-day search for the body of Sgt. La David Johnson, and findings are not expected for at least another month.

“If ISIS did carry out the attack, why didn't it claim it — especially after its claims of responsibility for attacks like Las Vegas and dozens of others which contain no direct connection to it?” Katz wrote.

Pro-ISIS media groups and channels have reacted with “just crickets” and not posted any celebratory graphics or social media messages.

“The silence is strange for the killing of American soldiers, which would in many ways be the most valuable type of attack a group like ISIS could capitalize on,” Katz wrote.