Gaps in U.S. intelligence led to the failure of a mission in Syria to rescue hostages held by Islamic State militants, including American journalists James Foley and Steven Sotloff, according to a published report.

The Wall Street Journal reports that the July 3 raid on an oil storage facility, a mission for which Delta Force commandos drilled for weeks, took place too late, as officials believe the hostages were moved by the militants just days before.

"(The site) was a dry hole," a senior U.S. military official told the paper.

The report corroborates a claim made earlier this week by a Pentagon official to Fox News, who said there was a delay regarding the question of whether to act to save Foley from ISIS militants. The Sunday Times of London first reported that the delay was 30 days. The former Pentagon official described a White House that was hesitant and continually asking for "the intelligence to build up more."

Other problems affecting the mission included a lack of informants on the ground, and a country the U.S. first approached about providing a base for the operation didn't want its territory used as the launch pad, the Wall Street Journal reported.

Also, the U.S. had limited visibility in Syria, and a senior administration official told the paper that the only Pentagon requests for surveillance flights came just before the mission. The problem was exacerbated by the strong communication discipline of the Islamic State, also known as ISIS, which made it harder to track hostages due to the subsequent lack of informants who could fill intelligence gaps.

U.S. officials do not believe ISIS militants were tipped off, but also do not rule out the possibility.

One model for the operation was the 2011 raid into Pakistan that killed Usama bin Laden, though current and former U.S. defense and government officials told the Journal that this operation was in many ways a far bigger gamble.

Fox News' Catherine Herridge contributed to this report.

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