Washington - A string of leadership and procedural failings - coupled with basic navigational and communication errors - lead to Iran's humiliating capture of 10 American sailors in January, a US Navy probe released on Thursday found.The investigation into the January 12 incident in the Persian Gulf says the captains and crews of two riverine patrol boats that veered wildly off course had been derelict in their duties.In all, nine Navy personnel - three of whom were actually on the boats that were meant to head from Kuwait to Bahrain - have been disciplined or will face disciplinary action."The investigation found a lack of leadership, a disregard for risk management processes and proper mission-planning standards," Vice Admiral Chris Aquilino told reporters. "If the guidance provided ... had been followed, this event could have been prevented."Iranian media broadcast humiliating images of the US sailors during their detention, showing them kneeling on their boats at gunpoint with their hands on their heads.Though the sailors were held for less than 24 hours, the incident was a major embarrassment for the US Navy and President Barack Obama.The United States carefully avoided escalating the situation, maintaining a conciliatory tone with Tehran days ahead of the implementation of a historic international deal over Iran's nuclear programme.Destined for troubleThe ill-fated mission was destined for trouble from the get go, the report found.Originally, the two boats were supposed to go from Kuwait on a 480km trip to Bahrain, the longest such sailing the crews had ever conducted. But the mission got off to a late start, so the crews attempted to take a shortcut to make up time, investigators found.This "deviation" caused them to unknowingly enter Saudi Arabian waters, and then stray into Iranian territorial seas off the coast of Farsi Island. The sailors saw "land masses", but did not realise where they were."Crewmembers speculated as to whether these were Saudi Islands, rocks or oil platforms," the probe states. "None of the crew believed that any of the masses were an Iranian island."The engineer on one boat even looked at an app on his smartphone to try to figure out what the land mass was, but the phone only displayed a "long Arabic name" and no other information.Less than two miles from the island, one of the boats broke down and stopped in the water. As crews worked to fix it, two Iranian Revolutionary Guard Corps Navy vessels approached with their guns uncovered. Shortly after, the Americans fixed the mechanical problem and attempted to flee, only to be blocked.The Navy has already relieved three officers of their commands, one of whom was on one of the boats. Six other people in the case face non-judicial punishments.