LUTTIG, Circuit Judge:

Appellee Jose Padilla, a United States citizen, associated with forces hostile to the United States in Afghanistan and took up arms against United States forces in that country in our war against al Qaeda. Upon his escape to Pakistan from the battlefield in Afghanistan, Padilla was recruited, trained, funded, and equipped by al Qaeda leaders to continue prosecution of the war in the United States by blowing up apartment buildings in this country. Padilla flew to the United States on May 8, 2002, to begin carrying out his assignment, but was arrested by civilian law enforcement authorities upon his arrival at O\ufffdHare International Airport in Chicago.

We conclude that the President does possess such authority pursuant to the Authorization for Use of Military Force Joint Resolution enacted by Congress in the wake of the attacks on the United States of September 11, 2001. Accordingly, the judgment of the district court is reversed.

Al Qaeda operatives recruited Jose Padilla, a United States citizen, to train for jihad in Afghanistan in February 2000, while Padilla was on a religious pilgrimage to Saudi Arabia.[footnote 1] J.A. 18-19. Subsequently, Padilla met with al Qaeda operatives in Afghanistan, received explosives training in an al Qaeda affiliated camp, and served as an armed guard at what he understood to be a Taliban outpost. Id. at 19-20. When United States military operations began in Afghanistan, Padilla and other al Qaeda operatives moved from safehouse to safehouse to evade bombing or capture. Id. at 20. Padilla was, on the facts with which we are presented, \ufffdarmed and present in a combat zone during armed conflict between al Qaeda/Taliban forces and the armed forces of the United States.\ufffd Id. at 21.

Padilla eventually escaped to Pakistan, armed with an assault rifle. Id. at 20-21. Once in Pakistan, Padilla met with Khalid Sheikh Mohammad, a senior al Qaeda operations planner, who directed Padilla to travel to the United States for the purpose of blowing up apartment buildings, in continued prosecution of al Qaeda\ufffds war of terror against the United States. See id. at 22. After receiving further training, as well as cash, travel documents, and communication devices, Padilla flew to the United

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[1] For purposes of Padilla\ufffds summary judgment motion, the parties have [link|http://dictionary.reference.com/search?q=stipulated|stipulated] to the facts as set forth by the government. J.A. 30-31. It is only on these facts that we consider whether the President has the authority to detain Padilla.

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States in order to carry out his accepted assignment. Id. at 22-
23.

Upon arrival at Chicago\ufffds O\ufffdHare International Airport on May 8, 2002, Padilla was detained by FBI agents, who interviewed and eventually arrested him pursuant to a material witness warrant issued by the district court for the Southern District of New York in conjunction with a grand jury investigation of the September 11 attacks. Id. at 93. Padilla was transported to New York, where he was held at a civilian correctional facility until, on June 9, 2002, the President designated him an \ufffdenemy combatant\ufffd against the United States and directed the Secretary of Defense to take him into military custody. Id. at 16, 94. Since his delivery into the custody of military authorities, Padilla has been detained at a naval brig in South Carolina. Id. at 162-63.

2.

Padilla also argues, and the district court held, that Padilla\ufffds military detention is \ufffdneither necessary nor appropriate\ufffd because he is amenable to criminal prosecution. J.A. 172. Related to this argument, Padilla attempts to distinguish Quirin from his case on the grounds that he has simply been detained, unlike Haupt who was charged and tried in Quirin. Neither the argument nor the attempted distinction is convincing.

As to the fact that Padilla can be prosecuted, the availability of criminal process does not distinguish him from Hamdi. If the mere availability of criminal prosecution rendered detention unnecessary within the meaning of the AUMF, then Hamdi\ufffds detention would have been unnecessary and therefore unauthorized, since he too was detained in the United States and

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amenable to criminal prosecution. We are convinced, in any event, that the availability of criminal process cannot be determinative of the power to detain, if for no other reason than that criminal prosecution may well not achieve the very purpose for which detention is authorized in the first place -- the prevention of return to the field of battle. Equally important, in many instances criminal prosecution would impede the Executive in its efforts to gather intelligence from the detainee and to restrict the detainee\ufffds communication with confederates so as to ensure that the detainee does not pose a continuing threat to national security even as he is confined \ufffd- impediments that would render military detention not only an appropriate, but also the necessary, course of action to be taken in the interest of national security.

4.

Finally, Padilla argues that, even if his detention is authorized by the AUMF, it is unlawful under Ex parte Milligan, 71 U.S. (4 Wall.) 2 (1866). In Milligan, the Supreme Court held that a United States citizen associated with an anti-Union secret society but unaffiliated with the Confederate army could not be tried by a military tribunal while access to civilian courts was open and unobstructed. Id. at 6-7, 121. Milligan purported to restrict the power of Congress as well as the power of the President. Id. at 121-22 (\ufffd[N]o usage of war could sanction a military trial . . . for any offence whatever of a citizen in civil life, in nowise connected with the military service. Congress could grant no such power . . .\ufffd). Quirin, however, confirmed that Milligan does not extend to enemy combatants. As the Court in Quirin explained, the Milligan Court\ufffds reasoning had \ufffdparticular reference to the facts before it,\ufffd namely, that Milligan was not \ufffda part of or associated with the armed forces of the enemy.\ufffd See 317 U.S. at 45. The Hamdi plurality in turn reaffirmed this limitation on the reach of Milligan, emphasizing that Quirin, a unanimous opinion, \ufffdboth postdates and clarifies

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Milligan.\ufffd 124 S. Ct. at 2643. Thus confined, Milligan is inapposite here because Padilla, unlike Milligan, associated with, and has taken up arms against the forces of the United States on behalf of, an enemy of the United States.