The AP said officials are concerned about a possible attack coming from the Arabian peninsula and possibly occurring in the Middle East and North Africa.
The Wall Street Journal published the entire alert, and an excerpt is published below:
The Department of State alerts U.S. citizens to the continued potential for terrorist attacks, particularly in the Middle East and North Africa, and possibly occurring in or emanating from the Arabian Peninsula. Current information suggests that al-Qa’ida and affiliated organizations continue to plan terrorist attacks both in the region and beyond, and that they may focus efforts to conduct attacks in the period between now and the end of August. This Travel Alert expires on August 31, 2013.