Vietnamese navy sailors march during a parade marking their 70th National Day at Ba Dinh square in Hanoi, Vietnam September 2, 2015. REUTERS/Kham

BEIJING (Reuters) - The militaries of China and Vietnam should deepen their exchanges, communication and friendship, China’s defense minister said during a visit to Hanoi, amid a festering territorial dispute in the South China Sea.

The two communist-led states’ claims in the South China Sea came to a head in 2014, when Beijing parked an oil rig in waters off the Vietnamese coast, leading to anti-China riots.

Since then they have exchanged high-level visits, including a trip by Chinese President Xi Jinping to Hanoi last year.

Meeting Vietnam Communist Party chief Nguyen Phu Trong, Chinese Defence Minister Chang Wanquan said the two sides should strive to maintain the close ties forged in the past by leaders Mao Zedong and Ho Chi Minh.

The two militaries should “increase high level exchanges and strategic communication, increase friendly feelings, deepen border defense exchanges and practical cooperation on U.N. peacekeeping, military academic research and the defense industry”, Chang said, in a statement carried late on Monday by China’s Defence Ministry.

While there was no direct mention of the South China Sea, the ministry said the commander of China’s South China Sea fleet, Shen Jinlong, attended the meeting.

Last month, tensions heightened between the two nations over territorial sovereignty in the South China Sea after Taiwan and U.S. officials said Beijing had placed surface-to-air missiles on Woody Island, part of the Paracel archipelago that China controls.

Vietnam called China’s actions a serious infringement of its sovereignty over the Paracels.

China claims most of the South China Sea, through which about $5 trillion in ship-borne trade passes every year. Its Southeast Asian neighbors Brunei, Malaysia, the Philippines and Vietnam, also claim parts of the sea, as does Taiwan.