World

Photo: The Canadian Press. All rights reserved.

A security guard walks in front of the U.S. Embassy in Manila, Philippines, Thursday, Sept. 13, 2012 as it's flag is on half mast following the death of US diplomats in Libya. Manila police tightened security in the area following the attack that killed the U.S. envoy and other diplomats in Libya. (AP Photo/Aaron Favila)

Security was increased at American embassies and consulates around the world on Thursday following an attack that killed the U.S. ambassador in Libya, while the U.S. urged its citizens abroad to be vigilant.

Guards and police special forces were seen carrying assault rifles outside the U.S. Embassy in the Philippine capital, while embassy guards gestured to a photographer to stop taking pictures.

President Barack Obama ordered increased security at American missions around the world after Ambassador Chris Stevens and three other Americans were killed Tuesday in an attack on the U.S. Consulate in Benghazi, Libya.

The attack was presumed to have been triggered by a provocative American film that depicts the Islamic prophet Muhammad in disrespectful ways, but U.S. officials are investigating whether it was a terrorist strike planned to mark the 11th anniversary of the attacks of Sept. 11, 2001.

Chanting "death to America," hundreds of protesters angered by the film stormed the U.S. Embassy compound in Yemen's capital and burned the American flag on Thursday.

The Yemeni Embassy in Washington condemned the attack and vowed to ensure the safety of foreign diplomats and to step up security measures around their missions in the country.

Indonesia's government has condemned the anti-Islam film, "Innocence of Muslims," whose trailer has gone viral on YouTube. But there has been no public reaction so far in the world's most populous Muslim nation, even though it is prone to large protests. Officials called on Indonesians to stay calm ahead of Friday prayers, when demonstrations often take place.

The U.S. Embassy in the Indonesian capital, Jakarta, issued a security message to American citizens advising them to pay close attention to their surroundings and to avoid large crowds that might turn violent.

"These events are a reminder to all of us that the security situation in any location can change rapidly and in unexpected ways," it said.

Indonesia's government has asked Google, which owns YouTube, to help block online access to "Innocence of Muslims," said Gatot Dewabroto, a Communication Ministry spokesman. It was available Thursday morning, but could not be viewed by afternoon.