Washington —  The U.S. military is directing commercial ships towards a route in the Strait of Hormuz farther from Iran that the Navy has spent weeks clearing. The U.S. warns that transiting the normal route could be "extremely hazardous" because of mines laid in the strait by Iran. 

The notice to mariners posted the same day the U.S. began its latest effort, "Project Freedom," to reopen at least part of the Strait of Hormuz. As part of the operation, forces under U.S. Central Command will coordinate with commercial ships to guide them through a cleared path in the strait.

At a briefing Tuesday, the Pentagon displayed a graphic saying Iran had laid new mines in the Strait of Hormuz on April 23. In March, CBS News reported there were about a dozen Iranian mines in the strait. That same month, the Pentagon tasked MQ-9 Reaper drones with conducting mine sweeper support throughout the critical waterway. 

The National Geospatial-Intelligence Agency, the Defense Department's arm for collecting and analyzing satellite imagery and geospatial data, has also been tapped for mine hunting duties, according to two U.S. officials who spoke to CBS News on the condition of anonymity to discuss national security issues. 

"It is already well reported that Iran has laid mines in the Strait of Hormuz, though not extensively," Capt. Tim Hawkins, a spokesman for U.S. Central Command, told CBS News when asked how many mines are in the Strait.  

"We've been addressing this matter in past weeks, including by clearing an effective pathway ships can use to safely transit. We will continue to take steps to ensure opportunities remain for ships to complete their journeys safely," Hawkins said in the statement.

When it was reported in March that Iran had laid mines, President Trump denied the U.S. had any knowledge of it, saying, "we have no reports of them doing so." The Pentagon also said at the time there was "no clear evidence" that mines had been dropped in the strait, but in recent days, the administration has acknowledged the presence of some mines. 

"I don't know if people appreciate how outrageous this is," Secretary of State Marco Rubio said Tuesday at a White House briefing. "That any country would try to fire at, to sink commercial vessels or put mines in the water — both of these things are illegal." 

On April 24, Defense Secretary Pete Hegseth warned Iran that laying any more mines would constitute a violation of the ceasefire. 

"If there's attempts to lay – recklessly and irresponsibly – lay more mines, we're going to deal with that. It's a violation of the ceasefire," Hegseth said.

On Tuesday when asked about the threat of mines, Hegseth said, "If there are mines identified, it would be something that our — some of our units could undertake or the world could undertake. But right now, we know we have a lane of safe passage that commercial shipping can flow through."

So far, two U.S. commercial ships have left the Persian Gulf since Project Freedom began. That's a small fraction of the 1,550 commercial vessels Joint Chiefs Chairman Gen. Dan Caine said have been stuck in the Gulf. 

Hegseth said "hundreds more ships from nations around the world are lining up to transit" but neither Hegseth nor Caine set any expectations for how many are expected to cross in the coming days. 

They both described Project Freedom as a "defensive operation" that is "temporary in duration," separate from the bombing campaign, Operation Epic Fury. On Tuesday, Rubio said Epic Fury "is over" and "concluded." 

Iran has said its threat against the strait is a response to the bombing and will continue until the U.S. military ends its blockade on Iranian ports.