As recently as April 16 - four days after Spicer's and Trump's comments - it was steaming in the opposite direction, into the Indian Ocean, more than 4830km from the Korean Peninsula. It is now actually headed towards the Sea of Japan, according to the Administration.
Spicer insisted today that he, Trump and Mattis didn't mislead the media. And his defence harks back to the infamous Bill Clinton quote about how "it depends upon what the meaning of the word 'is' is".
Here's what Spicer said:
"The President said that we have an armada going towards the peninsula. That's a fact. It happened. It is happening, rather ... The statement that was put out was that the Carl Vinson Group was headed to the Korean Peninsula. It is headed to the Korean Peninsula ... We said that it was heading there, and it was heading there - it is heading there ... If there was an impression, then there should have been clarification from people who were seeking it."
So, basically, as long as the ultimate destination of the Carl Vinson was the Sea of Japan, that means it was correct to say it "is" heading there. Even as it was travelling in the opposite direction four days after you say it was heading there, it was still heading there.
This explanation will undoubtedly satisfy the many people who have given Spicer and the Trump White House the benefit of the doubt over significantly more clear-cut falsehoods and messaging failures.
But - and this is the key - there was a narrative out there that a US aircraft carrier was headed into a very significant and conspicuous part of the western Pacific Ocean at a very key and tense time.
North Korea was about to test a missile, and the Trump Administration was ratcheting up US rhetoric about a potential standoff. Without that context, the omission would be forgivable; but this was big news, worthy of giving people a completely accurate picture.
There is a difference in politics between saying something that is plausible/defensible and saying something that is accurate. The former may allow you to get past a controversy, but it doesn't instill confidence among people that you will provide accurate information going forward.
Spicer and the White House nonetheless seem to err on the side of the former, repeatedly.
Whether they deliberately misled us or somehow didn't realise the narrative of confrontation that was quickly forming in the western Pacific, it's yet another strike against their credibility. And it's why it's getting very hard to give them the benefit of the doubt on stuff like this.