The Philippines and the United States began their main annual military exercises on Monday on a low key and a limited scale. The 12-day "Balikatan", or "shoulder to shoulder", joint military drills could serve as a barometer of the decades-old alliance. Some media reports say the number of troops taking part in this year's drills is less than half that in 2015, and the focus is only on anti-terrorism and disaster-response operations - in sharp contrast to the drills held when Benigno Aquino III was the Philippine president.

The "shoulder to shoulder" war games, begun in 1991, have been held almost regularly except for the brief interruption between 1995 and 1999. In recent years, many observers saw the annual exercises as a strategic maneuvering of former US president Barack Obama to push forward his "rebalancing to Asia" strategy. The military drills even served Aquino III's ulterior motive of confronting China over the South China Sea disputes and using it as a pretext to strengthen the Philippines' maritime defense and combat capabilities. And the drills, as expected, raised tensions in the region as they were staged near disputed waters.

However, Philippine President Rodrigo Duterte has sought to improve ties with China after taking office and play down the importance of his country's alliance with the United States. Duterte has also made some unfriendly remarks against the US, raising a lot of eyebrows in Washington and other Western capitals.