(CNN) The US State Department announced Friday that it was offering two "up to $5 million" rewards for information leading to the capture of ISIS in the Greater Sahara militants that were responsible for the October 4, 2017 ambush in Niger that killed four American soldiers and sparked a lengthy investigation into the incident's circumstances.

The State Department's Rewards for Justice program said Friday that it was offering two $5 million rewards, one for Adnan Abu Walid al-Sahrawi, a leader of ISIS-GS who claimed responsibility for the ambush in January 2018.

A second reward of up to $5 million is being offered "for information leading to the arrest or conviction in any country of any individual who bears responsibility for this act of terror," the State Department said, referring to the ambush that killed four American soldiers and four Nigerien soldiers.

TWO NEW REWARD OFFERS -- UP TO $5 MILLION EACH.



Seeking info on:



1. ISIS-GS leader Abu Walid



2. Those responsible for 10/4/2017 ambush of U.S. & Nigerien forces near Tongo Tongo, Niger



Absolute confidentiality. Relocation possible. More info at: https://t.co/NXX0swzsVk pic.twitter.com/S6MykLqWU9 — Rewards for Justice (@Rewards4Justice) October 4, 2019

Two Americans and eight Nigeriens were also wounded in the encounter which sparked a Pentagon investigation which found multiple failures at various levels within the US military.

"Abu Walid first proclaimed his group's allegiance to ISIS in May 2015, and, in October 2016, ISIS acknowledged his pledge," the State Department said, saying that ISIS-GS emerged when Abu Walid and his followers split from an al Qaeda splinter group based in Africa.

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