The U.S. military is planning to build a $125 million compound to hold war crimes trials at Guantanamo Bay Naval Base, including a two-courtroom facility, dining areas and accommodations for as many as 1,200 people.

The elaborate facility, scheduled to be completed by July, represents one of the most significant upgrades at the isolated base in southeast Cuba since it began taking in detainees in January 2002.

The Pentagon has not yet submitted the proposal to Congress, which must approve the expenditure.

Details of the compound were provided in a "presolicitation notice" posted on the Internet for potential government contractors. The plans described in the document, dated Nov. 3, were first reported by The Miami Herald on Friday.

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The design for the compound, to be constructed near an existing courtroom, includes residential quarters, dining areas and work spaces for those involved in the trials. The contractor would also be responsible for creating "a secure perimeter," according to the posting.

Among the suspects facing war crimes trials at Guantanamo are 14 "high-value" detainees who were recently transferred from secret CIA custody. The group includes Abu Zubaydah, believed to be a link between Osama bin Laden and many al-Qaida cells, and Khalid Sheik Mohammed, the suspected mastermind of the Sept. 11, 2001, attacks.

The U.S. government is drafting new rules for the trials under the Military Commissions Act, which President signed last month. The U.S. Supreme Court had declared previous efforts to try Guantanamo detainees unconstitutional.

Previously, 10 detainees had been charged with crimes, and it is expected that they would be charged again under the new law. Some 70 detainees are expected to be charged, military officials have said. There are currently some 430 detainees at Guantanamo.