The State Department, in an update on country profiles on terrorism, said that more than half of the terrorist attacks last year were in Afghanistan, Iraq and Pakistan.
U.S. combat forces left Iraq in 2011. The country's security situation has declined steadily since.
For Afghanistan, 2014 marks the end of an international military intervention meant to ensure the Taliban and al-Qaida no longer have a safe haven there. A missile allegedly fired from U.S.-operated drone aircraft reportedly killed a top Taliban commander in Pakistan this week. U.S. forces killed al-Qaida leader Osama bin Laden in 2011 in Pakistan.
"As a result of leadership losses, (al-Qaida's) core's ability to direct activities and attacks has diminished, as its leaders focus increasingly on survival," the State Department report said.
U.S. President Barack Obama said during a recent national security address that al-Qaida was on the run. The State Department report said that a weakened al-Qaida core meant its affiliates in the Middle East and North Africa were more independent, however.
"We are facing a more decentralized and geographically dispersed terrorist threat," the State Department report said.