Photo: The Canadian Press

First, Donald Trump threatened to rip up NAFTA. Then he didn't. This week he did again. Now, he's saying he won't. But maybe, he says, he'll change his mind again and rip it up if he can't get a good deal.

"A negotiating ploy," said Gary Hufbauer of the Peterson Institute, a top U.S. expert on the North American Free Trade Agreement. "True to Trump's style. The only surprise was the quick reversal (this week)."

It involves the concept that negotiating clout stems from the power to walk away. That power belongs to parties who don't fear the WATNA — the acronym for Worst Alternative To A Negotiated Agreement.

And right now, it seems, some people aren't sweating about the WATNA.

For starters, there's the U.S. Congress. Trump needs Congress to move and it hasn't. It's not only slow-walking the appointment of a trade czar, but has yet to approve a notice that would allow negotiations to start in 90 days. And the clock is ticking. If there's no deal by next April, the Mexicans warn it probably can't happen next year because of their national election. Canada's stance is wait-and-see.

Trade expert Laura Dawson explains the basic challenge for the U.S. president: He wants others to feel some fear. And it's not clear anyone's palms are sweating over the risk that NAFTA talks derail, the status quo continues, and Trump's big campaign promise to renegotiate crashes into oblivion.

"The alternative to a renegotiated NAFTA has been the status quo. And the status quo is not too bad (for them)," said Dawson, the head of the Canada Institute at Washington's Wilson Center.