The National Post reports in its Tuesday edition that the latest arbitrary deadline to a gratuitous threat made by an untrustworthy President falls this week when Aug. 19 arrives and the United States does or does not introduce 50-per-cent tariffs on a package of Canadian goods. The Post's Kelly McParland writes that Canada would be far better off in the long run avoiding any sort of agreement that lets Washington claim the slightest victory in its attempt to bully concessions out of Ottawa. He says it's better to walk away and let the White House face the consequences. Under this administration, any agreement reached will likely be meaningless. As long as Mr. Trump is president, the U.S. can't be trusted to honour its commitments -- a tariff deal could be signed one moment and disregarded the next. Until its leadership changes, any agreement with the U.S. will bring ongoing uncertainty. Even if Republicans lose in the midterms, the President's capacity to create confusion will persist until at least 2028, especially given the time needed to restore America's reputation. Whatever piece of paper negotiators wave should a last-minute "deal" be reached won't be worth the ink wasted on the signatures.