The U.S. government has strengthened its monitoring on Libya in the wake of a deadly attack by armed gunmen on the U.S. Consulate in Benghazi.

The U.S. military will send two destroyers equipped with cruise missiles to waters near Libya and boost surveillance there using unmanned reconnaissance planes. It already sent a team of some 40 antiterrorism elite marines to improve security at the U.S. Embassy in Tripoli.

The U.S. Federal Bureau of Investigation will dispatch its agents to Libya to collect evidence from the assault.

The U.S. government will focus its investigation on finding out whether the attack was planned in advance to coincide with the eleventh anniversary of the September eleventh, 2001 terrorist attacks.