Philippine security forces failed to prevent numerous terrorist attacks in Mindanao last year and President Duterte's war on drugs was an added burden on them, the US State Department said in a report this week.
The report said terrorist groups were able to plan bombings, shootings and ambushes "against targets of their choice," as shown by discovery of a bomb near the US Embassy in Manila on Nov. 28.
"Philippine military and police counterterrorism efforts kept up pressure on terrorist organisations but were unable to prevent numerous attacks against government, public and private facilities primarily in central and western Mindanao," said the State Department in its latest Country Reports on Terrorism issued on July 19.
The emergence of Islamic State (IS)-affiliated groups, kidnappings, attacks on government forces and bombings indicate that "domestic and international terrorism remained a serious problem" in 2016, it added.
Factions of the Abu Sayyaf Group (ASG), the Maute Group, or the Dawlah Islamiyah Lanao, and Ansar-al Khalifah Philippines have pledged allegiance to IS, which named ASG leader Isnilon Hapilon as its leader for Southeast Asia.
Unclear jurisdiction and coordination among counterterrorism units led to "inefficient investigations and response to terrorist incidents," the report said.
"The focus on counternarcotics has increased workload and operational tempo for security forces" it added.
Specialized police also did not have the necessary equipment for their work, it said.
The beheading of two Canadian men in April and June were among last year's notable terrorist actions, the report said.
It also cited clashes between government troops and New People's Army guerrillas in eastern Mindanao in July that killed seven soldiers.
The following month, 50 gunmen linked to Maute Group attacked a jail in Marawi City and freed eight comrades, it said.
The bloodiest attack took place on Sept. 2 in Mr. Duterte's hometown of Davao City where a bombing killed 15 and wounded more than 40 others. Several suspects linked to the Bangsamoro Islamic Freedom fighters and the Maute Group were arrested.
On Nov. 24, Maute Group fighters seized the town centre of Butig, Lanao del Sur province, resulting in six days of fighting that killed dozens of extremists.