WASHINGTON -- US President Donald Trump said Wednesday that the United States is in talks with Iran over "tariff and sanctions relief," while also threatening 50-percent tariffs on any country supplying weapons to Tehran.

"The United States will work closely with Iran, which we have determined has gone through what will be a very productive Regime Change!" Trump said on his Truth Social account.

There will be "no enrichment of Uranium," and the United States would cooperate with Iran to dig up and remove deeply buried "nuclear dust," he said.

He noted that many parts of the US-proposed 15-point ceasefire plan have already been agreed to.

Minutes later, in a separate post, Trump threatened 50-percent tariffs "effective immediately" on any country supplying military weapons to Iran. "There will be no exclusions or exemptions!" he said.

On Tuesday, the United States and Iran agreed to a two-week ceasefire. The two sides are scheduled to begin negotiations in the Pakistani capital of Islamabad on Friday.

In response to Washington's ceasefire plan, Tehran put forward a 10-point proposal that includes a US commitment to ensure no further acts of aggression, continued Iranian control of the Strait of Hormuz, acceptance of Iran's nuclear enrichment rights, and the lifting of sanctions, among others, Iran's semi-official Mehr News Agency reported.