Iran and Oman reach accord on Strait of Hormuz, Revolutionary Guards say

Though active hostilities between the U.S. and Iran have largely subsided in recent weeks, diplomatic efforts to reach a peace deal have stalled, and continuing attacks on ships mean passage through the Strait of Hormuz remains perilous.

Iran announced a blacklist on Sunday of 45 ships in an apparent effort to stop ship-to-ship transfers used by Gulf energy producers to evade the Iranian blockade. Some companies plan to stop using vessels added to the blacklist, sources said.

In an effort to tighten pressure on Iran's economy, the United States earlier this week threatened to punish countries that continue to do business with Iran, but said it would not impose penalties immediately.

The sanctions did not feature Chinese financial institutions suspected of facilitating oil exports from Iran that the U.S. blockade has cut.