A fleet of warships President Donald Trump claimed he had deployed into waters near the Korean Peninsula were in fact heading in the opposite direction.
The move was designed as a show of force against North Korea's "reckless" nuclear threat and prompted fears of an imminent war.
"We are sending an armada. Very powerful. We have submarines. Very powerful, far more powerful than the aircraft carrier, that I can tell you," said Mr Trump.
But the "armada", headed by the supercarrier USS Carl Vinson, was in fact steaming the other way to take part in military exercises with the Australian Navy in the Indian Ocean.
As North Korean leader Kim Jong-Un led a huge show of military strength - parading the country's new submarine-based ballistic missiles and carrying out a failed missile test - the flotilla of US warships was about 5,600 miles away.
It came to light after the US Navy posted a photo online of the aircraft carrier sailing through the Sunda Strait between Sumatra and Java in Indonesia.
The US military's Pacific Command has now explained that it had to complete the training with Australia, and that the strike group was now "proceeding to the Western Pacific as ordered" and should arrive near the Korean Peninsula early next week.
North Korea expert Joel Wit, at the 38 North monitoring group, said it raised questions about the Trump administration's credibility.
"If you threaten them and your threat is not credible, it's only going to undermine whatever your policy toward them is," he said.
'Overwhelming and effective' response
Despite the embarrassing revelation, US vice president Mike Pence warned North Korea not to test the resolve of America's military, promising it would make an "overwhelming and effective" response to any use of conventional or nuclear weapons.
Speaking aboard the USS Ronald Reagan aircraft carrier at the US Yokosuka naval base in Tokyo Bay, Mr Pence said the Trump administration would continue to "work diligently" with allies such as Japan, China and other global powers to apply economic and diplomatic pressure on Pyongyang.
But he added: "As all of you know, readiness is the key.
"The United States of America will always seek peace but under President Trump, the shield stands guard and the sword stands ready.
"Those who would challenge our resolve or readiness should know we will defeat any attack and meet any use of conventional or nuclear weapons with an overwhelming and effective American response."
