North Korea’s military parade on Saturday, more than rallying its citizens, appeared intended to send a message to the rest of us: The country is seeking a program sophisticated enough to fire a guaranteed nuclear retaliation in any war, including one day against the United States.

In 2013, when North Korea unveiled a map with a war plan for nuclear strikes against major American cities, “we all fell out of our chairs laughing,” said Melissa R. Hanham, an analyst at the Middlebury Institute of International Studies in Monterey, Calif. After a series of breakthroughs, including those shown on Saturday, they’re not laughing anymore, Ms. Hanham said: “The more they roll out, the more it looks like that is their actual plan.”

That plan was conveyed in four missile systems that were paraded for the first time, two of which were new altogether. Here are what the systems reveal about North Korea’s rapidly growing capabilities and how the country could use them in a war.