The two provocative events were not unrelated. The more Trump escalates his rhetorical assault on North Korea, the more Russia and China—the world powers with the strongest ties to Pyongyang—have countered with veiled threats of their own directed at the United States and its allies.

Beijing and Moscow, possessing arguably the second- and third-most-powerful fleets in the world after the U.S. Navy, are building a metaphorical wall at sea that could contain the American armada in the event Trump drives the United States to war with North Korea. In June, two U.S. aircraft carriers —the greatest concentration of American naval might in months—sailed through the Sea of Japan near the Koreas.

The five-day Russian-Chinese war game, which includes training events on land in Russia, began on Sept. 18. The date itself apparently was no accident.