>> Iran's elite Islamic revolutionary guard sends 5 military vessels to monitor US warships on a trip through the Strait of Hormuz, coming as close as 500 yards.>> And we've only been on board for a short period of time, but already an Iranian ship over my left-hand shoulder right there is trailing this vessel as the US Central Command's Chief General Votel tours.
>> Later, four Iranian speedboats approached, three with mounted machine guns. One of them cut its engines and watched as the New Orleans and its escort, a Navy guided missile destroyer, the USS Stout, passed by. For US Army General Joseph Votel, the approaches on Monday were a safe but worrying reminder of how little time American forces have to decide whether ships might pose a threat.
>> I think what you probably learned here today is that it's measured in minutes, but they really have an opportunity to make the right decisions. And so it is critically important that we understand what is happening, that we try to communicate and understand their intent and keep them from miscalculation, doing things that would cause us to go to a lethal type of response.
>> US officials stress that such approaches fell within the category of professional interactions. But the Navy says some 10% are classified as unsafe, abnormal, or unprofessional. The US military's concerns about Iran's behavior and places like the Strait of Hormuz, one of the world's most important oil shipping channels, had persisted despite the nuclear accord struck July last year.
Iran agreed to curb its nuclear program in exchange for relief from economic sanctions.