For most Americans, the Iranian hostage crisis that began in 1979 and carried on for 444 days ended the day Ronald Reagan was inaugurated. For the families of Shane Bauer, Josh Fattal and even Sarah Shourd, who on Tuesday was released from Iran on a $500,000 bail, that nightmare is far from over.

The three young Americans were taken prisoner by Iran more than a year ago when they apparently strayed over the Iranian border while backpacking in Iraqi Kurdistan. As with other foreigners who have come into the clutches of Iran's security ministries—American reporter Roxana Saberi or French academic Clotilde Reiss—the three were charged with espionage, which potentially carries a death sentence.

Iran uses hostages as bargaining chips in its diplomacy, either to humiliate its enemies—as it did with the British sailors it captured in 2007—or to extract concessions from them. The regime reportedly has demanded the release of 11 Iranians it claims are being held in the West, including a former general in the Revolutionary Guards who is believed to have defected in 2006.

For Mr. Fattal and Mr. Bauer, that means their ordeal is likely far from over. Ms. Shourd may also remain on the hook, too, as the regime could require that she return to "testify" should her two friends be put on trial. This may seem a relatively small cruelty, given the way the regime treats its own people. But it's another reminder of the menace it poses to any person, or nation, that wanders into its traps.