The Bush administration has long pushed the idea that when going into Iraq, the United States was "defeating the enemy there so we won't have to fight them here," but a study done by Mother Jones magazine shows that rather than defeating terrorism, the war in Iraq is apparently making things worse.
Overall, Mother Jones found, there has been a sevenfold increase in terror attacks worldwide since the invasion of Iraq. Moreover, when Mother Jones separated Iraq and Afghanistan, which might reasonably be expected to host an increase in terrorism, it still found that terrorism worldwide was up by 35 percent. Attacks on Westerners were up 25 percent.
A summary of the study can be read here; the full report is here.