Participants in Hamas' Oct. 7 terrorist attack against Israel received specialized training in Iran, The Wall Street Journal reported Wednesday.

Officers of the Quds Force, the foreign-operations arm of Iran's Islamic Revolutionary Guard Corps (IRGC), trained about 500 militants from Hamas and an aligned terrorist group, Palestinian Islamic Jihad, the Journal reported, citing people familiar with intelligence related to the assault. Senior Palestinian officials and Iranian Brig. Gen. Esmail Qaani, the head of Quds Force, also attended.

More than 1,400 Israelis were killed in the terrorist attack, the worst single day slaughter of Jews since the Holocaust. More than 200 were taken to Gaza as hostages, although a few have since been released.

Since the terrorist attack, Israel has bombarded Gaza through aerial strikes, and it has been preparing for a major ground assault to root out Hamas terrorists and rescue hostages.

The Wall Street Journal, citing senior Hamas and Hezbollah officials, has reported the Quds Force helped plan the attack and gave the green light during a meeting in Beirut on Oct. 2 with leaders of Hamas and Hezbollah, which is also backed by Iran. The Journal reported this was corroborated by an adviser to the Syrian government and a European official.

U.S. officials said Iran has regularly trained militants, but they have no indications of a mass training right before the attack.

"This sort of operation is very difficult to do without Hezbollah and IRGC support. Hamas does not have the capability to do that," Saeid Golkar, an IRGC expert at the University of Tennessee at Chattanooga, told the Journal.

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