Six main criminal activities used by terrorists to gain financing have been identified: (1) illicit drug distribution; (2) fraud; (3) stolen baby formula; (4) intellectual property theft; (5) cigarette smuggling; and (6) informal value transfer systems. In order to carry out terrorist activities, terrorists need robust and low-key funding sources. Many of these funding sources originate in the United States and involve illegal activities designed to fulfill the complimentary goals of financing terrorism while undermining the American economy. The author describes each type of the major six illegal activities used by terrorists. In one plot uncovered by authorities, over 300 people with terrorist links had smuggled enough pseudoephedrine into the country to manufacture 370,000 pounds of methamphetamine. Other terrorists prefer to engage in numerous types of fraud, including identity theft for profit, credit card, welfare, social security, food stamp, and coupon fraud. Terrorists groups have also engaged in a scheme to sell stolen baby formula. In the late 1990s, Texas authorities discovered that shoplifting gangs were paying drug addicts and indigent people $1 per can for stealing baby formula, which they would then resell. One of the largest stolen baby formula rings netted $44 million in 18 months. To put this figure into context, the author reports that the September 11th terrorist attacks in the United States cost approximately $500,000. Cigarette smuggling is another means terrorists use to make money. In this type of scheme, cigarettes are bought in a State with lower taxes, like North Carolina, and resold in other States with higher taxes, such as Michigan. Each trip between North Carolina and Michigan with a van load of cigarettes can net terrorists $3,000 to $10,000. Finally, informal value transfer systems and alternative remittance systems operate below legal oversight and are ripe for abuse by terrorists. Endnotes