If special counsel Robert S. Mueller III one day proves that someone on the 2016 Trump campaign colluded with Russia, a top White House spokesman may live to regret what he said Sunday.

Appearing on ABC's “This Week,” deputy White House press secretary Raj Shah said President Trump would have been aware of any such collusion if it did occur.

“There's been zero evidence, after a year of investigation, that we've seen of actual collusion between the Russian government and the Trump campaign,” Shah said. “The president, who would be aware of any types of efforts, has been pretty clear, understands and knows that there is no collusion.

“And so, as he has said, this investigation is everything from a hoax to a witch hunt. It's not going to find any evidence of collusion.”

Okay, but what if it does? Shah has just ruled out the idea that someone else could have colluded with Russia without Trump's knowledge. If we find out one day that someone within the campaign did collude, Shah's remarks suggest that Trump had to have known about it. There's no other way to read them.

For instance, take that meeting with the Russian lawyer that Donald Trump Jr. organized — and Jared Kushner and Paul Manafort attended — in the name of obtaining derogatory information about Hillary Clinton. A major question hanging over the Russia investigation is whether the president had any knowledge of or involvement in that meeting. Shah is suggesting that even if something such as that meeting were proved to be untoward and illegal, Trump would have known about it.

“It was a really foolish thing to say — and one that they very likely will regret,” former federal prosecutor Peter Zeidenberg said.

But might it actually be legally problematic? On that question, Shah might be able to rest a little easier. Experts say that although Shah's comment might have been inadvisable, it's unlikely to serve as retroactive proof that Trump would have known about yet-to-be-proved collusion.

Former assistant U.S. attorney Jeffrey Cramer said that the comment “eliminates the defense that maybe some people in his campaign met with and had an agreement or understanding with the Russians without Trump’s knowledge.” But he said that because it's just Shah's opinion, it probably would have no bearing on the case.

“I’m sure he will have to walk back the comment,” former federal prosecutor John Lauro said, “but I don’t view it as a damaging admission or having legal significance.”

Added former assistant U.S. attorney Patrick Cotter: “Neither a statement by his spokesman or even by himself can create or expand his legal liability, any more than such statements could decrease his legal liability.”

Even from a strictly public-relations standpoint, though, the comment may not age well and contradicts some past defenses offered by White House and Trump campaign aides.

As recently as last week, former Trump campaign aide Sam Nunberg said he thought that Carter Page, a Trump campaign foreign policy adviser, had colluded with Russia. Manafort's relationship with the Russians is well established, too, and it's not inconceivable that he might have freelanced on a thing or two during the campaign — although any such allegation was not included in his indictment.

Trump, meanwhile, hasn't exactly shown a talent for micromanagement when it comes to either his White House or his campaign. Even those around him have suggested that the campaign was simply too disorganized and chaotic to have colluded with the Russian government. And given Trump's tendency to pass the buck when things go wrong, it's not difficult to see something untoward having happened and Trump blaming someone else.

But according to his own spokesman, Trump would have known about it.