Why did spanish colonists begin to rely more heavily on the atlantic slave trade by the mid-1500s?

This was due to the large scale operation the Spaniards were conducting in their colonies.  They needed labor that can do this type of work.  This later led to the Spaniards getting involved in the slave trade as well since it was a convenient way to get workers for them.

the recent bombing of the uss cole is one of many incidents of terrorism directed against the united states. more than 40 percent of the world’s terrorism is directed against u.s. targets.   pursue the alleged perpetrators through the criminal justice system, and still others would beef up intelligence capabilities. to deal with potential attacks involving weapons of mass destruction, some analysts advocate extending the reach of law enforcement agencies or spending more on domestic preparedness programs; others would encourage a policy of u.s. military restraint overseas to attempt to reduce the motivation for terrorist attacks on u.s. targets.