The Pentagon is preparing an assessment on who was responsible for the weekend attack on Saudi oil facilities and hopes to make it public, a U.S. defense official said.

The official couldn’t confirm or deny a CBS News report that the U.S. has identified locations in southern Iran from which it believes more than 20 drones and cruise missiles were launched. The official had said the assessment could be released within 48 hours, but another official said the timing and nature of the presentation aren’t yet decided.

U.S. experts are conducting an intense examination of evidence on the ground in Saudi Arabia and reviewing intelligence such as radar tracks from the region, while the Pentagon’s Defense Intelligence Agency is working to pull together a public presentation of declassified material, according to the first official.

While Secretary of State Michael Pompeo has asserted that Iran was clearly behind the attack -- rejecting the claim of responsibility by Iranian-backed Houthi rebels in Yemen -- President Donald Trump has said he is holding off a judgment on who was responsible and what action should be taken in response until he hears more directly from Saudi Arabia.

“Our intelligence community at this very hour is working diligently to review the evidence,” Vice President Mike Pence said Tuesday in a speech in Washington.

“I promise you, we’re ready,” Pence said at the conservative Heritage Foundation. “As the president said, we don’t want war with anybody, but the United States is prepared. We’re locked and loaded.”

Intelligence Document

Lawmakers were allowed to view a 3-page classified intelligence document this week, which Wisconsin Senator Ron Johnson, the Republican chairman of the Senate Homeland Security Committee, said left him “100% convinced” that Iran is responsible.

“I think it’s pretty convincing. I think Iran’s responsible for that,” Johnson said Tuesday. “But let’s absolutely confirm that and then we’ll have to determine what action we can take, hopefully with our allies.”

Even if Iran is found to be responsible for the attack, there is disagreement among senators on what action can be taken without Congress’s approval. Some Republicans, like Florida Senator Marco Rubio and South Carolina‘s Lindsey Graham, said a U.S. strike on Iran would be covered by an existing war authorization.

Other senators like Kentucky Republican Rand Paul and Connecticut Democrat Chris Murphy cautioned against U.S. involvement in another Middle East conflict. They said even if the intelligence points conclusively to Iran, Congress would have to approve any military action against that country.

”I don’t think we are at war with Iran, nor have they attacked us,” Paul said. “They attacked Saudi Arabia. That would be a good question for Saudi Arabia whether they are at war with Iran. But, they didn’t attack us.”