First there was Barack Obama in Ohio, threatening to scrap the North American Free Trade Agreement. Now, with another rust-belt primary in the offing -- Pennsylvania -- Hillary Clinton has made the same threat. NAFTA must be renegotiated. If that isn't done, she'll rip it up.

Please, kids. Can we get serious?

The U.S. is not in a position to arbitrarily dictate changes to NAFTA. As Prime Minister Stephen Harper and Industry Minister David Emerson have said, that's not how negotiations work. If the deal were reopened, Canada would have demands, too. So would Mexico.

Consider energy for instance. As NAFTA now stands, U.S. companies have guaranteed tariff-free market access to Canadian energy resources. And Canada has the same access to U.S. energy.

That's a good deal for Canada. It allows our oil and gas exporters uninhibited entry into the massive U.S. market, which they otherwise might not have. And it's good for the U.S. -- for the obvious reason that it needs Canadian oil and natural gas, among other resources.

Now let's talk about energy security. In the late 1980s and early '90s, when the North American Free Trade was first negotiated, the Cold War was ending and America reigned supreme.

Today the world is different. What do Saudi Arabia, Iran, Iraq, Kuwait, the UAE, Venezuela, Russia, Libya, and Nigeria have in common? They're nine of the world's top 10 holders of proven petroleum reserves. Yikes.

The 10th country, and No. 2 on the list in terms of the size of resource, is Canada.

The fact that Canada's reserves are geographically accessible, in a stable democracy, and sheltered by a free trade agreement, is a priceless strategic asset to the United States. No president -- Democrat or Republican -- will jeopardize America's access to that resource.

Clinton is no more "serious" about abrogating free trade than she was about landing "under fire" in Bosnia. It's campaign hooey, and not to be believed.