President Trump would never even think of doing that!

So we've heard again and again, from Trump allies apparently trying to pre-commit the president to not doing something stupid or dangerous that he's obviously inclined to do.

They said it when they claimed, way back when, that Trump had no interest in starting any trade wars. They said it when Trump was contemplating defying a Supreme Court ruling on the census citizenship question. And they said it when Trump made his supposedly unintentionally racist comments about four congresswomen of color, when they wanted to bridle his itchy Twitter finger.

Each time, right after such pronouncements, Trump either immediately did the stupid or dangerous thing, or threatened to do it soon.

With his latest threats to weaken the dollar, we're seeing this pattern once again.

Trump, obsessed by the prospect that someone somewhere might be cheating in a way he hasn't yet tried, has lately been complaining about perceived currency manipulation. The dollar is strong, the president believes, because other countries are deliberately devaluing their currencies to make U.S. exports more expensive, and thereby foil his trade agenda.

It's true that the dollar has been rallying, and that this makes U.S.-made products look less competitive to foreign buyers.

Trump's own loose fiscal policies are also likely contributing to the dollar's strength, at least if you believe that the tax cuts are working as Trump's supporters claim.

So what's a president to do?

Last week, the president convened a meeting of his economic advisers to brainstorm whether and how the administration could take its own action to devalue the dollar.

It's not clear what Trump's Treasury might do. It could sell off the limited stash of dollar-denominated assets from its Exchange Stabilization Fund. Or there's another mechanism so dangerous that I'm almost nervous to mention it in a national newspaper, in case Trump hadn't already thought of it: He could threaten to default on our debt.

In any case, shortly after that meeting, White House advisers were quick to assure journalists that Trump had unambiguously sided against massive currency manipulation. White House National Economic Council Director Larry Kudlow even went on CNBC and declared that Trump had "ruled out" a currency intervention.

The White House valued a "steady, reliable, dependable dollar," Kudlow said.

Predictably, mere hours after Kudlow's comments, Trump told reporters the opposite: "I could do that in two seconds if I want to," Trump said. "I didn't say I'm not going to do something."

Trump has never prized consistency as a virtue. And even if he did, he doesn't understand the underlying economic issues well enough to achieve it.

Catherine Rampell's email address is crampell@washpost.com. Follow her on Twitter, @crampell.