U.S. Republican leaders castigated President Barack Obama for "pretending" that all's well with the country's relations with Iran despite its "illegal" seizure and detention of 10 American sailors and their two patrol boats on Tuesday.

Although their Iranian captors did not allegedly hurt them, the sailors were made to kneel with their hands clasped behind their heads, in what many sources described as a humiliating and demeaning posture that likely violated the Geneva Conventions.

They were eventually released on Wednesday after detaining them at a Iranian naval base for 16 hours.

Iranian media had field day, releasing the video and images of the Americans' capture and surrender, TIME reported.

The commander of the U.S. unit was even seen in the video apologising for the incident, saying, "It was a mistake that was our fault and we apologise for our mistake."

In Thursday night's Republican presidential debate, Donald Trump blamed Obama for putting America to shame, describing the incident as "an indication of where the hell we're going."

Ben Carson noted that while Obama was talking about his "accomplishments" during his final State of the Union Address on Tuesday, "10 of our American sailors are being held by Iran."

Jeb Bush also slammed Obama, saying the incident once again exposed his administration's "humiliatingly weak Iran policy."

Marco Rubio added: "Iran is testing the boundaries of our resolve."

"The Administration is pretending as if nothing out of the ordinary has occurred," said Senator John McCain (R-Arizona), the chairman of the armed services committee. "These sailors were 'arrested' in apparent violation of international law and centuries of maritime custom and tradition," he added, noting that the Geneva Conventions bans the release of images of identifiable detained troops.

Senator Tom Cotton (R-Arkansas) said earlier he had many questions for the Pentagon.

"Where exactly were the sailors intercepted? Why were they detained instead of being merely escorted into international waters? What was the nature of the technical malfunctions on both vessels? What is the condition of our boats? Was sensitive equipment compromised? Why were the sailors not permitted to contact U.S. higher headquarters in the region for the 16 hours they were detained?" Cotton asked.

"I'm also curious why American officials would characterise Iran as assisting a distressed vessel when Iran has characterised the incident as U.S. ships trespassing into its waters and 'snooping.' Iran does not deserve the benefit of the doubt.

"Until we have answers to these questions, we should not be rationalising Iran's behavior in an incident that was highly abnormal. Our sailors never should have been detained in the first place, and blithely accepting such action will only embolden the ... ayatollahs who wish to do harm to Americans and our allies in the Arabian Gulf," he added.

The tense diplomatic standoff took place just days before Iran is to start receiving the billions of dollars of seized funds as part of the Iran nuclear deal.

Reports from Iran said the Pentagon was forced to make a "grovelling apology" in a bid to get the sailors released, the Daily Mail reported.

However, U.S. State Department spokesman John Kirby insisted there was no official apology sent to Iran because there was "nothing to apologise for."

But U.S. State Secretary John Kerry did tell Tehran that the release of the sailors could be turned into a "good story" for both countries, AFP reported.

Kerry reportedly called Foreign Minister Mohammad Javad Zarif at least five times on Tuesday to secure the safe release of the boat crews after they strayed into Iranian territorial waters in the Gulf and were captured.