President Donald Trump announced Monday that the United States will impose a 25 percent tariff on any country conducting business with Iran, escalating economic pressure on Tehran as the regime faces its most severe challenge in decades from mass anti government protests that have left hundreds dead.

"Effective immediately, any Country doing business with the Islamic Republic of Iran will pay a Tariff of 25% on any and all businesses being done with the United States of America," Trump wrote on Truth Social. "This Order is final and conclusive."

The announcement came with no details on enforcement mechanisms, scope, or possible exemptions, leaving major questions about how the sweeping measure would be implemented.