John M. "Jack" Keane (born February 1, 1943) is a retired four-star general and former Vice Chief of Staff of the United States Army, and a defense analyst currently serving as chairman of the board for the Institute for the Study of War.
Keane was born in 1943 in Manhattan, New York, the son of Elizabeth (Davis) and John Keane. He has a brother, Ronald. Keane married Theresa Doyle in 1965 and has two sons. His wife died in 2016 after having Parkinson's disease for 14 years. 
Keane attended Fordham University, where he participated in The National Society of Pershing Rifles, graduating with a bachelor's degree in accounting in 1966. He then attended Western Kentucky University, graduating with a master's degree in philosophy. He later attended the Command and General Staff College and the Army War College.
Keane served in the Vietnam War as a paratrooper. He later served in U.S. engagements in Somalia, Haiti, Bosnia and Kosovo. His commands include the 1st Brigade,10th Mountain Division, 101st Airborne Division and the XVIII Airborne Corps.
In 1991 Keane saved the life of General David Petraeus during a live fire exercise. According to Keane, Petraeus was shot "accidentally, standing right next to me, and I had to fight to save his life. He had a hole about the size of a quarter in his back and is gushing with blood, and we stopped the bleeding and got him on a helicopter and got him to a surgeon and so we were sort of bonded ever since that time."
Keane retired from military service in 2003. He now works as a national security analyst for Fox News. He has served an advisory role in the management of the U.S. occupation of Iraq, as a member of the Defense Policy Board Advisory Committee. In January 2007, Keane and scholar Frederick W. Kagan released a policy paper, entitled "Choosing Victory: A Plan for Success in Iraq", through the American Enterprise Institute that called for bringing security by putting around 30,000 additional American troops there for a period of at least 18 months. In part convinced by this paper, President George W. Bush ordered on January 10, 2007, the deployment of 21,500 additional troops to Iraq, most of whom would be deployed to Baghdad, this deployment has been nicknamed the 2007 "surge".
Of his initial meeting with President Bush regarding the surge, Keane said he made a phone call to Newt Gingrich to ask his advice prior to the meeting. As Keane said in 2014,
Gingrich gave me some good advice. He said, "Look, Jack. Most people go in the Oval Office, even people who go in there a lot, have a tendency in front of the President of the United States to always leave something on the table." He said, "Don’t leave anything on the table." He said, "You’re going to get about 15 minutes at best and put it all out there. And when you walk out of that room, feel good that you got it all out there." So that was sound advice, and I did put it all out there.
Keane currently sits on the board of directors of General Dynamics, and is a consultant/strategic advisor for Academi. He has also lobbied on behalf of AM General, the firm that produces the Humvee. Keane became the executive chairman of AM General in October 2016.
Military awards Keane has received include two Defense Distinguished Service Medals, two Army Distinguished Service Medals, the Silver Star, Five Legion of Merits, the Bronze Star, Two Meritorious Service Medal s, one Army Commendation Medal, the Joint Chiefs Service Badge, the Humanitarian Service Medal, Ranger Tab, Combat Infantryman Badge, Master Parachutist Badge, and Air Assault Badge.