Sen. Lindsey Graham, R-S.C., predicted Sunday that the U.S.-Iran framework agreement signed last week will collapse, adding that President Trump is prepared to seize the Strait of Hormuz by force if it does.

Graham, who told CBS he spent 4 1/2 hours with Trump on Friday, made the comments on "Face the Nation" as Vice President JD Vance opened nuclear talks with Iranian officials at a Swiss mountain resort.

"If you don't have a diplomatic path through the MOU, then you have to go to war or some other form of coercion," Graham said. "Let's try this. Let's try a diplomatic solution. I think it's going to fail."

He said that if talks break down, "President Trump is going to take the Strait of Hormuz over by force. The United States will control the Strait of Hormuz. We'll charge a fee for all those who go through to pay for the operation."

Graham issued a parallel warning over Lebanon, where fighting between Israel and Iran-backed Hezbollah has strained the ceasefire.

"If Iran continues to attack Israel and Lebanon, the new policy will be, we'll hit Iran," he said. "When you use Hezbollah to attack Israel, I think the new policy will be, we will attack Iran."

He added that if the Iranians contest U.S. control of the strait, "we will obliterate them."

Graham also walked back his earlier opposition to a $300 billion reconstruction fund for Iran that he had compared to "a Marshall Plan with a Nazi still in charge for Germany."

His reversal turns on who pays.

"Before, I thought the money was coming from the West," he said. "Can you imagine if Saudi Arabia, Qatar, and the United Arab Emirates invest $300 billion in Iran? That would tell me that Iran has changed."

He said he doubted the Gulf states would commit the money.

Trump has publicly disputed any U.S. role in the fund.

At the G7 summit in Evian, France, on Wednesday, he told reporters, "We are not investing in it, and we do not have a fund," adding that the U.S. has not asked Gulf countries to put up money.

The 14-point memorandum signed in Islamabad commits the U.S., "with regional partners," to develop a plan with at least $300 billion for Iran's reconstruction.

The talks in Switzerland opened the 60-day window set by the MOU for resolving Iran's nuclear program and unresolved regional disputes.

Energy Secretary Chris Wright said Sunday that 67 ships transited the strait Saturday and 55 on Friday under U.S. military escort along a southern route, with oil flows "about equal to where we were before the war."

Iran on Saturday declared the waterway closed again, citing Israeli operations in Lebanon.

Reuters contributed to this report.