China is training and supporting an increasingly sophisticated fishing militia to sail into the South China Sea, where the Asian powerhouse is engaged in territorial disputes with the Philippines, Vietnam and several other countries in the region.

A fishing fleet based in a port town on Hainan island — China's southern-most point — has been provided with military training and subsidies, as well as fuel for the training exercises, provincial government officials, regional diplomats and fishing company executives said in recent interviews, according to Reuters.

"The maritime militia is expanding because of the country's need for it, and because of the desire of the fishermen to engage in national service, protecting our country's interests," an advisor to the Hainan government told Reuters. The advisor said the training was being provided by city-level branches of the country's armed forces.

Diplomats and naval experts have reportedly raised concerns that the fishing militia could raise the risk of conflict with foreign navies in the strategic waterway through which $5 trillion of maritime trade passes each year.

China has stakes far-reaching claims in the South China Sea, claiming almost all of it as its own. Over the last few months, it has built artificial islands on reefs and has conducted naval patrols to assert its control.

The United States has been conducting sea and air patrols near artificial islands China is constructing in the disputed Spratlys archipelago. The U.S. says its freedom of navigation operations are designed to emphasize that the South China Sea, home to some of the world’s busiest shipping lanes, remains international waters, adding that it would increase the "freedom of navigation" sail-bys around the disputed area.