Republicans on Capitol Hill said Monday they need more information about the agreement between the United States and Iran announced by President Donald Trump, and some are expressing skepticism as they ask the White House for details.

The agreement announced Sunday to end the war in Iran, set for a ceremonial signing Friday in Geneva, is centered around reopening the Strait of Hormuz and lifting the United States’ naval blockade in the region, along with financial incentives for Iran if it meets certain benchmarks. But Senate Republicans and Democrats who returned to Washington on Monday said there were still many unanswered questions about the deal and they need thorough briefings before it is finalized.

“I just don’t know enough about it,” Senate Majority Leader John Thune, R-S.D., told reporters in the Capitol. “Even the people who follow this stuff closely up here don’t know that much about it.”

Congressional leaders and intelligence committees generally receive higher-level intelligence briefings before rank-and-file members, and they are notified of major developments before they are announced. But Thune said he had not been personally briefed on the deal.