Saudi Arabia on Saturday intercepted and safely destroyed a missile aimed at the capital city of Riyadh by Houthi rebels in neighboring Yemen, where a Saudi-led coalition is intervening to oppose the rebels in the Yemeni civil war.

After news of the missile broke, President Trump blamed the attack attempt on Iran. Like the Houthis and unlike the Sunni Saudis, Iran is predominantly loyal to the Shiite branch of Islam, and Tehran has long been accused of funneling arms and other support to the rebels' cause. Iran denied responsibility for Saturday's missile, and the Houthis claimed it, but Saudi Arabia echoed Trump's words, declaring on Monday Iran had committed an "act of war" and warning that Riyadh would respond accordingly.

The primary part of that response we've seen so far is the Saudi coalition's Monday decision to seal off Yemen from the outside world. The ostensible goals are to keep out Iranian weapons, starve the Houthi rebels of military support and bring Yemen's internal conflict to a close, but the blockade's real impact is to literally starve the Yemeni people.