If you just followed news reports on Ukraine, you might think that the war has settled into a long, grinding and somewhat boring slog. You would be wrong. Things are actually getting more dangerous by the day. For starters, the longer this war goes on, the more opportunity for catastrophic miscalculations — and the raw material for that is piling up fast and furious. Take the two high-profile leaks from American officials this past week about U.S. involvement in the Russia-Ukraine war: First, The Times disclosed that “the United States has provided intelligence about Russian units that has allowed Ukrainians...