The US Maritime Administration (MARAD) issued an advisory concerning the importance of vessels remaining vigilant when transiting the Sulu and Celebes Sea as all vessels in the area are at risk of attack.
According to the advisory:
U.S.-Flag vessels are advised to remain vigilant when transiting the Sulu and Celebes Seas in light of recent boardings and kidnappings that have taken place between sabah, malaysia and the southern philippines. There have been 13 reported kidnappings in this area this year, of which at least nine were reportedly linked to the Abu Sayyaf group
Previously when crewmember kidnappings took place in this area, only towing and fishing vessels were targeted. However, since October 2016, ASG has reportedly targeted two large commercial vessels and a private yacht. The level of violence has been high during some of these attacks, as was demonstrated on November 7, 2016 when kidnappers boarded a yacht, killed one female crewmember, and kidnapped the remaining crewmember. Thus far, no U.S. vessels have been involved in these incidents. Also read ReCAAP ISC incident alert for further details.
Mariners operating near this area are also advised to consult the department of state travel warning for this area at travel.state.gov/content/passports/en/alertswarnings/philippines-travel-warning.html
Source: US MARAD