John Brennan, the former head of the C.I.A., estimates the chance of a war with North Korea at 20 to 25 percent.

Joel S. Wit, a Korea expert at Johns Hopkins University, puts it at 40 percent.

Richard Haass, the president of the Council on Foreign Relations, says the odds may be somewhere around 50/50.

Yet we’re complacent: Neither the public nor the financial markets appreciate how high the risk is of a war, and how devastating one could be.

The Congressional Research Service last month estimated that as many as 300,000 people could die in the first few days of war — and that’s if it remains nonnuclear. If there is a nuclear exchange, “there easily could be a million deaths on the first day,” says Scott Sagan, an international security expert at Stanford.