U.S. military officers were flying in Sunday to serve as jurors in war-crimes proceedings as the Guantanamo tribunal system geared up for one of its busiest weeks under President Barack Obama.

The Pentagon is holding military commission sessions this week for two detainees: a young Canadian going on trial for the slaying of a U.S. soldier in Afghanistan and an aide to Osama bin Laden who is to be sentenced after pleading guilty in a deal with prosecutors.

The tribunal system that ground to a halt after Obama took office is coming alive with lawyers, human-rights observers and more than 30 journalists who are at the U.S. Navy base in southeastern Cuba to attend Monday's proceedings in two courtrooms....