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Retired Gen. John Allen was commander of American forces in Afghanistan

Allen developed a security plan for Israel, West Bank during Israeli-Palestinian negotiations

Ex-Marine caught up in David Petraeus scandal, but Defense Department cleared him

(CNN) —  

John Allen, the retired four-star Marine general and former commander of American forces in Afghanistan, will take on the role of coordinating the international coalition to battle ISIS, Secretary of State John Kerry announced Friday.

The move marks a return to the head of a difficult and challenging mission that bears no clear or obvious solutions for a successful outcome. Allen is a veteran of many of many of those.

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Allen is certainly familiar with the rocky terrain he is about to enter having been one of the top commanders in western Iraq during the “Sunni Awakening,” a program that worked to turn Sunni tribes in Anbar province against the al Qaeda affiliate then operating in Iraq.

The militant organization now swallowing portions of both Syria and Iraq that President Barack Obama has vowed to destroy is the successor to what was once that al Qaeda group.

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Allen graduated with honors from the U.S. Naval Academy in 1976, and has racked up a long and distinguished list of accomplishments both on the battlefields of Afghanistan and Iraq as well as an attempted role as peacemaker to one of the longest and most intractable conflicts in the Middle East.

Obama tapped him in 2011 to take command of the International Security Assistance Force in Afghanistan – the NATO-led coalition of military forces in that country – after Obama nominated Gen. David Petraeus, then that coalition’s commander, to become director of the CIA.

Allen was the first Marine tapped to head up the military effort in Afghanistan.

Kerry later appointed him to develop a security plan for Israel and the West Bank during negotiations between Israelis and Palestinians over the possibility of a future Palestinian state that eventually collapsed.

Before his command in Afghanistan, Allen was deputy commander at U.S. Central Command, which oversees all military operations in the Middle East.

He is also a decorated veteran of the armed forces, having received the Defense Distinguished Service Medal and the Defense Superior Service Medal among others.

While controversy mostly eluded his impressive rise to the top ranks of the U.S. military, Allen was briefly caught up in the 2012 scandal involving Petraeus’ infidelity that ultimately led the widely admired retired general to resign his CIA post.

An investigation into “flirtatious” email exchanges between Allen and Jill Kelley, the Florida woman whose complaints about threatening emails from Petraeus’ mistress, Paula Broadwell, brought the scandal into the public, led Allen to withdraw his nomination by Obama to become NATO’s supreme allied commander in 2013.

The Defense Department eventually cleared him of any wrongdoing, and Allen retired from the Marines.

Allen is the married father of two daughters and holds master’s degrees from Georgetown University, the Defense Intelligence College and the National War College.

CNN’s Alan Duke and Elise Labott contributed to this report.