71 killed in Israeli attack on Iran prison, official says

The Defense Intelligence Agency on Wednesday has released a statement describing its Iran bomb strike assessment as "a preliminary, low confidence assessment – not a final conclusion – and will continue to be refined as additional intelligence becomes available."

The statement adds that "we have still not been able to review the actual physical sites themselves, which will give us the best indication."

DIA is also working with the FBI and other agencies to investigate the leak of the assessment, it said.

-ABC News' Luis Martinez and Anne Flaherty

It would likely take "years" for the Iranians to rebuild all three nuclear facilities struck by the U.S. -- Natanz, Fordow and Esfahan -- because they were "destroyed," U.S. Director of National Intelligence Tulsi Gabbard said Wednesday.

Gabbard also criticized what she called the "propaganda media," accusing outlets of trying to "selectively release portions of illegally leaked classified intelligence assessments (intentionally leaving out the fact that the assessment was written with 'low confidence') to try to undermine President Trump’s decisive leadership and the brave servicemen and women who flawlessly executed a truly historic mission to keep the American people safe and secure."

Earlier in the week, CNN reported details from an early Defense Intelligence Agency assessment indicating that the U.S. strikes on Iran only set back its nuclear program by months.

Gabbard told ABC News on Monday that the U.S. strike against Iran obliterated "key Iranian capabilities needed to quickly assemble a nuclear weapon."

"The operation was a resounding success," Gabbard added.

-ABC News' Beatrice Peterson

Iran's Islamic Revolutionary Guard Corps commander in chief said on Wednesday that his fighters were ready to respond if Israel escalates again, as a fragile ceasefire continues to hold.

"We have never and will never trust this savage enemy. All our fighters have their fingers on the trigger. If the enemy makes a mistake, we will certainly respond with the same courageous defense as we did during the past twelve days. We will never hesitate for a moment in defending this country," Mohammad Pakpour, IRGC commander-in-chief, said.

Mossad Chief David Barnea on Wednesday thanked the CIA for its help in Israel's operations in Iran, saying the Israeli intelligence agency is continuing to keep a "close eye" on Iran.

"I want to express appreciation and gratitude to our central partner, the CIA, for the joint activity, for the operations that came to light. Also to the head of the CIA who supported the Mossad and for bringing forward the right decisions that ultimately made this operation possible," he said.

"We will continue to keep a close eye on all the projects in Iran that we know very well. We will be there [in Iran], as we have been there until now," Barnea noted.

-ABC News' Dana Savir and Will Gretsky