American forces in Iraq now hold some 300 prisoners tied to Iran’s intelligence agencies, Pajamas Media learned from both diplomatic and military sources.

This is believed, by both sources, to be a record number of prisoners tied to Iran. Virtually all were captured in the past two months.

This week’s seizure of 15 British sailors by Iran in the contested waters of the Shattab al-Arab, the ship channel that divides Iraq and Iran, may have been payback for the capture of record number of Iranian operatives inside Iraq. “It may be a bargaining chip,” one diplomatic source said.

The intelligence community is still debating whether the unlawful detainment of British sailors was ordered by Iran’s government or was presented to it as a fait accompli by relatively low-level Iranian Revolutionary Guards officers.

The roughly 300 prisoners held in Iraq—the number grows frequently—are either Iranian nationals or Shiites recruited from neighboring countries that are employed one of its almost two dozen intelligence or paramilitary services.

The record haul of Iran-linked prisoners may not be a sign of Iran’s increasing involvement in Iraq. The Islamic Republic’s participation in the Iraq war, which includes funding, arming and training both Shiite and Sunni militias, has been known to be significant for some time.

More likely, the large number of Iran-linked prisoners reflects a change in tactics following the arrival of Multinational Force Iraq commander Army Gen. David H. Petraeus. Previously, Iranians and other foreigners could not be picked up without a provable connection to terrorism. Now, American and allied forces are encouraged to seize militants based on a reasonable suspicion of involvement in insurgent attacks. This is consistent with Iraqi law.

The number of bombings associated with Iran-backed groups seems to be declining, although both sources cautioned it is too soon to be sure.

The Pentagon received “considerable pressure” from officials in the State department and CIA to release some or all of the Iran-linked prisoners to facilitate discussions between Secretary of State Condoleezza Rice and Iranian officials. Apparently, Gen. Petraeus sharply disagreed, saying that he intends to hold the prisoners “until they run out of information or we run out of food,” according to our sources who heard these remarks through channels...