Final answer:
President George W. Bush declared a war on terror following the September 11 terrorist attacks, targeting al-Qaeda and the Taliban in Afghanistan, and later Iraq under Saddam Hussein over presumed weapons of mass destruction and terrorist threats.
Step-by-step explanation:
After the September 11 terrorist attacks, President George W. Bush declared a war on terror. This declaration was made during an address to a joint session of Congress on September 20, 2001. Bush identified al-Qaeda leader Osama bin Laden as the perpetrator and demanded that Afghanistan's Taliban government, which was providing safe harbor to al-Qaeda, turn over bin Laden or face attack by the United States. This marked the beginning of the U.S. military campaign in Afghanistan, which was aimed at dismantling al-Qaeda and removing the Taliban from power. The war on terror was further expanded with the invasion of Iraq in 2003, under the pretext that Iraqi President Saddam Hussein possessed weapons of mass destruction and posed a significant threat to international security.