US President Donald Trump said he was sending "an armada" to Korean waters to potentially deal with threats from Pyongyang.
But its no-show has caused some South Koreans to question his leadership and strategy regarding their unpredictable neighbor in the north.
And as the country prepares to vote for a new president on May 9, the claim could have far-reaching implications for the two countries' relations.
"What Mr. Trump said was very important for the national security of South Korea," Presidential candidate Hong Joon-pyo told the Wall Street Journal.
"If that was a lie, then during Trump's term, South Korea will not trust whatever Trump says," said Hong, who is currently trailing in the polls.
South Korean media also seized on the conflicting reports on Trump's "armada" -- led by the aircraft carrier USS Carl Vinson.
One newspaper headline called it Trump's "Carl Vinson lie," and speculated that the Russian and Chinese leaders must have had a good laugh at its absence.
Meant to present a robust defense against a potential nuclear test by Pyongyang, the report likened the bluff to North Korea's shows of force, where "fake missiles" are paraded through the streets of the North Korean capital.
"Like North Korea, which is often accused of displaying fake missiles during military parades, is the United States, too, now employing 'bluffing' as its North Korea policy?" it asked.