AMMAN, Jordan — The extremists of the Islamic State managed to parlay their Japanese and Jordanian hostages into 12 days of worldwide publicity. But other than depleting their supply of foreign hostages, did they really accomplish anything?

Analysts who study terrorist groups were skeptical, and many said the militants’ tactics had backfired badly, particularly in Jordan. The extremists apparently killed two Japanese men, but failed to achieve either of their professed goals: $200 million in ransom, and the release of a female Iraqi suicide bomber from death row in Jordan.

Their threat to kill a captive Jordanian air force pilot (and their failure to produce evidence that he was alive) did not achieve the intended effect of undermining support for Jordan’s role in the international coalition bombing the Islamic State. Now even skeptical Jordanians have begun rallying around their government’s position and denouncing the extremists.

That shift comes as the Islamic State, also known as ISIS or ISIL, has nearly run out of Western or other foreign hostages, as fewer aid workers and journalists dare to enter Syrian territory. Last August, when the American-led bombing campaign began, the group held at least 23 Western hostages; now they are believed to have four hostages viewed as prominent internationally, including two Westerners. The extremists continue to hold an untold number of Syrians.