Analysts worry that terrorist attacks like those in Paris will remain difficult to detect

U.S. and French intelligence officials are leaning toward an assessment that the Paris terror attacks were inspired by al-Qaida but not directly supervised by the group.

One of the two brothers who carried out the attack at the Charlie Hebdo newspaper is believed to have traveled briefly to Yemen and met an al-Qaida leader. Yet U.S. intelligence officials are not convinced that the Paris attacks were directed from abroad.

Investigators also are not convinced that the man who killed five people in Paris in separate incidents coordinated with the brothers.

Such assessments place the attacks on a continuum of violence by disaffected individuals who have become sympathetic to al-Qaida, the Islamic State group or their ilk — yet are not involved in an international conspiracy that is easier to detect.