The embassy issued an advisory saying it has credible information that terrorists are targeting "Western aviation interests" in Saudi Arabia. It urges U.S. citizens to postpone non-essential travel to the kingdom.

The embassy's Public Affairs Officer, Carol Kalin, says the advisory follows recent terrorist attacks in Saudi Arabia, as well as other places.

"If you look around the world you will see, unfortunately, terrorist activities, certainly in Iraq, and unfortunately in other places," she said. "We would just ask everyone to remain vigilant in this period."

Attacks on western compounds in Riyadh in May killed 35 people.

The U.S. embassy in Riyadh warned last week of possible attacks on Western targets during the Muslim holy month of Ramadan, which started Monday. But the advisory is more detailed and refers to specific information received by the U.S. government.