Khat is an East African plant whose leaves are chewed as a mild stimulant in parts of East Africa and the Middle East, especially Yemen. Its primary active agents are cathine and cathinone.
How damaging the khat habit can be is a matter of considerable dispute. It’s illegal in the U.S., though openly available in some stores with East African and Middle Eastern clientele. In Israel, with its substantial Yemeni population, khat is not controlled, and not regarded as much of a problem; few Israelis of non-Yemeni origin are interested in it, and even among the Yemeni it tends to be a of old men.
However, according to an Israeli official I just met with, over the past couple of years some Israelis have begun to chemically extract cathinone from the plant for use by injection, and the associated injection practices have generated a substantial HIV problem in a country where previous HIV levels were quite low.
No, I can’t think of a specific policy moral to cap this tale, other than that drug-related activity is complex and hard to predict.