AFTAC's nuclear event detection mission is directly linked to its nuclear treaty-monitoring mission. AFTAC monitors signatory countries' compliance with the 1963 Limited Test Ban Treaty. This treaty prohibits nuclear testing anywhere but underground and prohibits the venting of nuclear debris or radiation from those tests into the atmosphere outside the country's national borders. AFTAC also monitors the Threshold Test Ban Treaty of 1974 and the Peaceful Nuclear Explosion Treaty of 1976. The 1974 treaty limits the size of underground nuclear tests to 150 kilotons, while the 1976 treaty prohibits the testing of nuclear devices outside of agreed treaty sites.