The United States has increased security at all its major airports and railway stations, and has taken a number of measures, that include temporary closure of its 22 diplomatic missions, following a "very specific" Al Qaeda threat emanating from the Arabian Peninsula.

President Barack Obama himself is keeping a close tab on the developments and the threat, which the officials did not disclose.National Security Advisor Susan Rice held a meeting of top US national security officers to review the potential terror threat coming from the Arabian Peninsula.