The United States and Iran traded defiant messages ahead of Monday’s expected announcement of new U.S. economic sanctions targeting Iran and potentially key trading partners such as China.

Nearly six months into the war, the two sides were no longer exchanging fire but had made little progress toward peace talks. Meanwhile, oil shipments through the Strait of Hormuz have virtually halted as Tehran seeks to preserve its leverage by threatening to strike unauthorized tankers attempting to pass through the strategic waterway.

U.S. Treasury Secretary Scott Bessent is scheduled to hold a news conference at 2:00 p.m. EDT (6:00 p.m. GMT) Monday, when he is expected to unveil what Washington has described as “the toughest sanctions in history” against Iran and urge China to cooperate with the United States.

China buys more than 80% of Iran’s seaborne oil exports, according to 2025 data from analytics firm Kpler. Beijing has called for diplomacy and a negotiated resolution.

Iranian Foreign Ministry spokesman Esmaeil Baghaei said Saturday that the expected U.S. sanctions announcement amounted to an “assertion of extraterritorial sovereignty over every independent member state of the United Nations.”