Six years ago, President Donald Trump hailed his US-Mexico-Canada Agreement, or USMCA, as the “fairest, most balanced, and beneficial trade agreement we have ever signed.”

Now, as the pact is up for review, Trump says he’s ready to abandon it.

“I’m not looking to renew it,” Trump said last month. “We don’t need anything that Canada has. We don’t need anything that Mexico has, but they need everything that we have. They have to treat us better.”

That’s not exactly true, but even if it were, Trump can’t simply scrap the deal.

The USMCA, which replaced the North American Free Trade Agreement, facilitates roughly $2 trillion in annual trade among the three neighboring countries. Supply chains — particularly in the auto industry — depend on the agreement’s duty-free provisions, with parts crossing the US, Mexican and Canadian borders multiple times before a finished vehicle rolls off the assembly line.