Iranian officials have threatened to forgo negotiations even as U.S. representatives plan to arrive in Pakistan for the meeting and a ceasefire is set to expire Wednesday.

Three vessels — two cargo ships and a fuel tanker — appeared to be attempting to transit the Strait of Hormuz early on Tuesday as US and Iranian blockades remained in place. The Shoja 2, an Iranian-flagged cargo vessel,

Tensions are high at the Strait of Hormuz and Iranian ports in the area affected by a U.S. blockade. CBS News' Charlie D'Agata reports, and "60 Minutes" correspondent has more on potential blueprints for operations to remove Iran's stockpile of highly enriched uranium.

An Iranian-flagged vessel, identified as the Touska, ignored warnings from U.S. forces and was ultimately disabled by the U.S. Navy before being boarded by

Iran threatened retaliation after the seizure in the Gulf of Oman, and it wasn't clear whether Tehran would attend talks in Pakistan, with a ceasefire set to expire Wednesday.

Last-minute ceasefire talks between the United States and Iran looked uncertain Tuesday as a two-week truce was set to expire and both countries warned that, without a deal, they were prepared to resume fighting.

No region of the world produces more oil and gas than the countries straddling the Persian Gulf, and most of it needs to travel by tanker through the Strait of Hormuz.

Both sides remain dug in rhetorically, with Donald Trump warning that "lots of bombs" will "start going off" if there’s no agreement before the ceasefire deadline.