The Navy's top officer said Thursday that an investigation into Iran's detention of 10 sailors and the seizure of their two riverine boats in the Arabian Gulf earlier this year showed that Iran broke international law.

"These two boats and their crew members had every right to be where they were on that day," said Chief of Naval Operations Adm. John Richardson during a press briefing.

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"The investigation concluded that Iran violated international law by impeding the boat's innocent passage transit and they violated sovereign immunity by boarding, searching and seizing the boats and by photographing and videotaping the crew," he said.

The investigation's conclusion now raises the question of whether and how the Obama administration will seek redress from Iran.

Richardson would not comment on whether he is aware of any steps the U.S. government will take in response.

"Our investigation didn't investigate that," Richardson said. "So I just want to confine our discussion today on what the investigation covered."

Richardson said the Navy has not directly expressed their displeasure with Iran, leaving it up to Secretary of State John Kerry John Forbes KerryThe Memo: Warning signs flash for Trump on debates Divided country, divided church TV ads favored Biden 2-1 in past month MORE.

Senate Armed Services Committee Chairman John McCain John Sidney McCainMomentum growing among Republicans for Supreme Court vote before Election Day McConnell urges GOP senators to 'keep your powder dry' on Supreme Court vacancy McSally says current Senate should vote on Trump nominee MORE (R-Ariz.) said the report confirmed Iran's "flagrant violations of international," and criticized the administration for thanking Iran for releasing the sailors.

“The Navy investigation confirms what has been obvious from the beginning: that Iran’s obstruction, boarding, and seizure of sovereign U.S. Navy vessels at gunpoint and the detention, interrogation, and recording of 10 American sailors were flagrant violations of international law," he said in a statement.

"Yet five months later, the Administration has shamefully failed to retract its craven statements of gratitude and praise for Iran’s illegal behavior. This Administration’s groveling to Iran has placed all American service members at greater risk," he added.

The January 12 incident came just hours before President Obama was to deliver his State of the Union address, and set off a diplomatic scramble to get the sailors released.

The incident was an embarrassment to the administration, which was defending a nuclear agreement with Iran that gave it sanctions relief in exchange for limits to its nuclear program.

The investigation also concluded that the crews of the boats were "derelict" in their duties, by going off course almost immediately after they began their transit from Kuwait to Bahrain in order to save time.

"The RCB boat captains and crews were derelict in performing their duties to expected norms and standards," the report said. "The crews' unplanned and unauthorized deviation caused them to transit unknowingly through Saudi Arabian territorial seas and then through Iranian territorial seas off the coast of Farsi Island."

When the boats were about 1.5 nautical miles from Farsi Island, one of the boats' engines broke down, the summary said.

Shortly thereafter, the Iranian navy approached the boats "in a threatening posture (with weapons uncovered)," it said. As the U.S. boats tried to "evade and then communicated with the Iranians," two more Iranian vessels arrived.

The U.S. boats were then forced to reposition to Farsi Island, the report said.

The report also found that some crew members gave the Iranians information about the capability of their boats and passwords to personal phones and laptops.

And although under standard rules of engagement, U.S. military personnel are obligated to defend their units, the captains leading the crews ordered their gunners to step away from their weapons.

"I didn't want to start a war with Iran," one of the captains said. "My thought at the end of the day was that no one had to die for a misunderstanding."

The Iranians held the sailors for 16 hours, later releasing video and pictures of the crews kneeling with their hands behind their heads.

Video was also released of one of the captains apologizing and another crew member wiping away tears.

Overall, the mission was plagued by poor decisions, bad training and little oversight, the investigation found.

Two senior officers have already been fired over the incident: Capt. Kyle Moses, which headed the task force that included the riverine units, and Cmdr. Eric Rasch, the commander of the riverine squadron.

The investigation recommended taking disciplinary or administration action against several members of the crew.

— Updated at 12:13 p.m.