MANILA, April 21 (UPI) -- The largest joint U.S.-Filipino military training exercise in 15 years began in the Philippines on Monday amid ongoing territorial disputes between China and its neighbors.
"Balikatan," meaning "shoulder-to-shoulder," is an annual training operation that in 2015 features more than 11,000 troops from the Philippines and the United States.
This year the United States sent over 6,000 troops to participate -- more than double the 2,500-strong force sent in 2014 -- while roughly 5,000 troops from the Philippines are taking part in the drill, compared to 3,000 last year.
Additionally, the U.S. Navy deployed three vessels and 76 aircraft for Balikatan, joining one ship and 15 planes from the Philippines.
The drill, which is in its 31st iteration, will last until April 30.
On the same day Balikatan 2015 commenced, the Philippines decried China's construction of artificial islands in territorial waters, releasing aerial photographs of the project in the Spratly Islands, which involves piling sand from the ocean floor onto coral reefs to create man-made islands. The masses feature buildings and airstrips.
Speaking at a press conference, Gen. Gregorio Pio Catapang, chief of state of the Philippine army, said the project would affect international shipping lanes and that the islands could be used for military purposes.
Catapang was quoted by NBC News as saying his country had "compelling reasons to raise our voice to tell the whole world the adverse effects of China's aggressiveness."
He also pointed out that 300 coral reefs would be destroyed as a result of the project, causing "irreversible and widespread damage" to the "biodiversity and ecological balance" in the region.
Filipino officials said Balikatan, even with its increased size, was not intended as a threat to China.
"No specific threat was factored in," Lt. Col. Marlowe Patria, the Philippines' spokesman for Balikatan 2015, told the Philippines Star. "We are just looking at ways to enhance our capability to defend ourselves."
China's island project in the South China Sea also brought it into territorial disputes with Vietnam, Malaysia, Brunei and Taiwan.
U.S. President Barack Obama expressed concern over the issue earlier this month, saying he believed it could be solved diplomatically but noting that China's smaller neighbors could not just be "elbowed aside."
Hong Lei, spokesman for China's foreign ministry, told NBC News the islands were to be used for "maritime search and rescue, disaster prevention and mitigation, marine science and research" and defended their construction as "justifiable and lawful."