US Vice President JD Vance said on Monday that Washington was in direct contact with Tehran, days before the expected signing of a framework agreement to end the war with Iran.
"We're dealing with everybody in the Iranian system," Vance told broadcaster CNBC, specifically mentioning the "political leadership" and "military side."
"We have some good relationships there, so this is going to be a successful negotiation, because we're not passing messages through various back channels anymore."
Pakistan and Oman had been acting as intermediaries during the conflict.
For the first time since 1979, senior US and Iranian officials met face-to-face for talks in Islamabad in April. The two countries do not maintain formal diplomatic relations.
"We expect to have a full spectrum of representatives at the negotiation on Friday," Vance said of signing ceremony due to take place in Switzerland.
Vance argued that Washington held the stronger position in the negotiations with the Iranian leadership. "We fundamentally have all the cards here," he told CNBC.
After weeks of negotiations, the United States and Iran agreed on Sunday to a framework accord to end their hostilities and reopen the Strait of Hormuz, although few details of the agreement have been made public.
Many observers have described the deal as an interim step in a diplomatic process that still faces significant obstacles.
