Tensions increased near the Persian Gulf on Tuesday as an Iranian ship intercepted a cargo ship in the Strait of Hormuz.

The Iranian vessel is said to have fired a shot across the bow of the ship. The U.S. Navy said it has positioned another destroyer in response.

The shipping company said that the crew members were safe, but it remains unclear why the vessel was seized.

FoxNews.com reports:

The Marshall Islands-flagged MV Maersk Tigris was en route Wednesday to Bandar Abbas, the main port for Iran's navy, under escort by Iranian patrol boats, according to Maersk Line, the company that had chartered it. Tehran has not offered any clarification on why it boarded the ship Tuesday, which comes at a critical time during Iran's relations with the United States and the West.

The Pentagon and State Department offered conflicting statements as to whether the U.S. has a responsibility to protect the ship.

"I am not aware of any specific agreement or treaty that calls for us to protect Marshallese vessels," a defense official told Fox News on Wednesday.

But a day earlier, State Department spokesman Jeff Rathke said otherwise.

“The security compact between the United States and the Republic of the Marshall Islands gives the U.S. authority and responsibility for security and defense matters that relate to the Marshall Islands, including matters related to vessels flying the Marshallese flag,” he said at a briefing.

The Marshall Islands -- officially known as the Republic of the Marshall Islands, and a former U.S. trust -- enjoys "associated state" status with the United States, meaning the U.S. agrees to defend the islands, provide economic subsidies and access to federally-funded social services. The islands have little natural resources, therefore in recent years have focused on expanding its service economy -- including delving into the shipping industry.

Fox News strategic analyst Lt. Col. Ralph Peters (Ret.) called the move a "hijacking" by Iran, but explained that the incident is not really about the United States. 

Peters said Tehran is trying to send a message to the Saudis, who have been conducting airstrikes against the Iran-backed Houthi rebels in Yemen.

"This was a warning shot across the bow of Saudi Arabia and the Gulf Emirates. ...Iran thinks strategically, they're very cunning. This was targeted at the Saudis and the Gulf Arabs, saying 'you keep messing with us, we can close the Strait of Hormuz any time.' And the Saudi and the Gulf oil goes through the Strait of Hormuz," said Peters.

Peters said the key is that the vessel involved in this case is a Marshall Islands-flagged container ship.

"They don't want to hit a U.S.-flagged carrier right now because we would be forced to respond," he said.

"This is Middle Eastern brinskmanship. We're peripheral players on this one. Nobody wants to escalate it, but things can spin out of control," said Peters.

Watch his full analysis above.