Embargo

A ban on trade with another country.

For example, in the 80s, then-President Carter issued an embargo on Russian grain. Americans could no longer ship grains to Russia, which caused U.S. farmers to suffer. Grain prices plummeted.

Embargos reflect only government regulatory restriction of market demand. They typically result in price increases in dramatic fashion. The U.S. has embargoed the import of the oh so awesome Cuban cigars for decades. They existed in nearly every smoke shop for the easy, one-time, "because you are my friend" price of $50 a stick. As the modern era lifts the embargo on cigars, prices have plummeted to "only" $15 or so a stick, and are likely headed south.