Saudi Arabia has charged that a missile launched from Yemen toward Riyadh’s international airport Saturday was supplied by Iran and assembled by Tehran’s Lebanese client, Hezbollah. It claims the right to “respond to Iran in the appropriate time and manner.” Yet the only action taken so far by the de facto Saudi ruler, Mohammed bin Salman, has been to besiege some of the world’s most desperate people – the civilian population of Yemen.

Yemen is suffering the fastest-growing cholera epidemic ever recorded, according to the U.N., with about 895,000 cases and nearly 2,200 deaths since April. At the same time, it is facing the world’s biggest food emergency, with 7 million people requiring urgent assistance.

According to U.N. figures, 27 percent of the cholera victims are under the age of 5. Officials estimate that juvenile cholera cases will reach 600,000 by the end of the year. Meanwhile, 2.2 million children are affected by either moderate or severe malnutrition.

Saudi Arabia bears heavy responsibility for this suffering. For 2½ years, it has pursued a ruthless but unwinnable war against ethnic Houthis who have captured much of Yemen. Bombing raids have repeatedly struck hospitals and food markets. Worse, in the name of preventing Iran from delivering weapons to the Houthis, the Saudis and their allies have closed the airport in the capital, Sanaa, to commercial traffic and slowed food imports at the nation’s largest port, Hodeida.

Now, in reaction to the missile firing, the Saudis have announced a more thorough closure of “all Yemeni ground, air and sea ports,” to prevent what they claim was the smuggling of missile parts into Yemen from Iran.

The blockade will not deter either Iran or the Houthis, but it could trigger a full-blown famine among innocent children. The Trump administration, which has blithely backed Crown Prince Salman in his reckless adventures, should consider the cost.