JAKARTA, Aug 3 (Aljazeera) - More than 5,000 soldiers from Indonesia, the United States and other countries have begun joint combat exercises on the Indonesian island of Sumatra, signalling stronger ties amid growing maritime activity by China in the Indo-Pacific region.

The annual military training, known as Garuda Shield, has been taking place since 2009. But this year sees the participation of several other countries, including Australia and Japan, making it the largest ever.

The joint exercises, which began on Wednesday, are designed to strengthen interoperability, capability, trust and cooperation in support of a free and open Indo-Pacific, the US embassy in Jakarta said in a statement.

“It’s a symbol of the US-Indonesia bond and the growing relationship between land forces in this consequential region,” Charles Flynn, commanding general of US Army Pacific, said in the statement. “Because land forces are the glue that binds the region’s security architecture together.”

Flynn and Indonesia’s military chief General Andika Perkasa opened the joint drills with a ceremony on Wednesday morning in Baturaja, a coastal town in South Sumatra province.

The exercises, encompassing army, navy, air force and marine drills, will last until August 14.

Al Jazeera’s Jessica Washington, reporting from Baturaja, said this year’s exercises mark an important shift from previous drills.

“They used to be just bilateral exercises, but now we are seeing a move to multilateralism involving other countries, not just as observers but as participants as well,” Washington said, noting that this year’s iteration has been called Super Garuda Shield due to its bigger size.

The planned two-week drills opened after China’s defence ministry said on Tuesday night it would conduct a series of targeted military operations to “safeguard national sovereignty” in response to US House Speaker Nancy Pelosi’s visit to self-governed Taiwan, which China claims as its territory to be annexed by force if necessary.

China has also been increasingly assertive over its claim to virtually the entire South China Sea.

While Indonesia and China enjoy generally positive ties, Jakarta has expressed concern about Chinese encroachment on its exclusive economic zone in the South China Sea, which China claims virtually in its entirety.

The US-Indonesia military exercises coincided with Pelosi’s arrival in Taiwan late on Tuesday, as the highest-ranking American official in 25 years to visit the self-ruled island. Beijing views visits by foreign government officials as recognition of the island’s sovereignty.

The Japan Ground Self-Defence Force is participating for the first time in the exercises, saying it promotes a “free and open” Indo-Pacific vision of security and trade with the US and other democracies in the region.

The expanded drills are seen by China as a threat. Chinese state media have accused the US of building an Indo-Pacific alliance, similar to NATO, as a means to intentionally provoke conflict.