Iran live updates: US officials say negotiations with Iran to resume

Iran's Supreme Leader Ayatollah Mojtaba Khamenei said on Saturday that avenging his slain predecessor and father was "the demand of the nation" and "must certainly" take place, according to a message released by state television.

Khamenei issued the message on the occasion of funeral ceremonies for his father, Ayatollah Ali Khamenei, held months after he was killed in the U.S.-Israeli airstrikes on February 28.

"We pledge to avenge the blood of the martyred leader and all the martyrs of these two wars from the criminal and disgraced killers," Khamenei said in the message.

-ABC News' Rashid Haddou

President Donald Trump said "1000 Missiles are Locked and Loaded and aimed at Iran," should the government attempt to assassinate him.

In a post on his social media platform, Trump said the U.S. military is "ready, willing, and able, for a one year period of time, subject to extension, to completely decimate and destroy all areas of Iran."

A U.S. official said that the question of nuclear dust "still very much is on the table" -- using a phrase to describe Iran's highly enriched uranium that remains covered in rubble after U.S. airstrikes.

"Either they're going to give us the nuclear dust or we have very low-cost military options to ensure that it remains buried underground forever," one U.S. official said.

The U.S. official later added that the nuclear materials are key to the deal.

"We have a lot of options if they resist giving the dust. There are continued military, diplomatic, economic leverage points. That's my point there, is that the United States fundamentally has the cards. We want the dust," the U.S. official said.

"But I want to be clear here that if we don't get the dust, we do not have a deal with Iran," the U.S. official said.

-ABC News' Michelle Stoddart

Senior U.S. officials say that the U.S. is demanding that Iran issue a public statement that "acknowledges all channels of the Strait of Hormuz are open and they're not shooting at ships anymore."

A U.S. official said that one of the key results they're expecting out of talks set for Saturday is that Iran will agree that the Strait of Hormuz will be open in the same way it was before the conflict.

"And we are expecting that as a result of the meeting in Oman tomorrow, that that will be their position. And if it's not their position, then it's not going to be a great day for them," the official later added.

-ABC News' Michelle Stoddard