US Pacific Commander Samuel Locklear has called on Beijing and Washington to improve communications through a naval hotline to defuse potential conflict.

Observers said on Friday the move is an attempt to deepen military relations between the United States and China. However, to achieve this the US should abandon its frequent maritime and air surveillance and reconnaissance activities against China, which have only led to distrust, the observers said.

Locklear said at a Pentagon news briefing that he wants a hotline to officers from the People's Liberation Army in case there is a crisis in the region.

"I don't have the ability to pick up the phone and talk directly to a PLA, or PLA navy, admiral or general at the time of a crisis, and we need to work on that," he said.

US Defense Secretary Chuck Hagel and Martin Dempsey, chairman of the Joint Chiefs of Staff, have the capabilities to reach out in a crisis and "we would hope it would work", Locklear added.

Bonnie Glaser, senior adviser for Asia at the Center for Strategic and International Studies, a think tank in Washington DC, said, "Military exchanges, including joint exercises, have developed in a positive direction. Nevertheless, there has not yet been agreement on ‘rules of the road' at sea or in the air, so accidents are still possible."

In December, a "near-miss" was reported between warships from China and the US in the South China Sea, which Glaser believes demonstrates the potential risk and highlights the need for better understanding of operational safety.

"This just highlights to both of us, to both the PLA and to the US military, that we have to do better at being able to communicate with each other in a way that allows us to not lead to miscalculation — which won't be productive in the security environment," Locklear said.

The low-key response from both sides after the South China Sea incident, and Locklear's remarks, indicate that China and the US are willing to enhance military-to-military trust and to protect already-fragile military ties, observers said.

"Locklear's remarks show that Washington would like to deepen military trust with China," said Jia Xiudong, a senior researcher on international affairs at the China Institute of International Studies.

"But what's more important than improving the hotline communication channels is that Washington should give up its maritime and air surveillance and reconnaissance activities against China," he said.

"These activities are challenging China's national security and will only hurt bilateral trust."

With increasing security concerns in the Asia-Pacific region, a growing number of naval forces from China and the US are operating in the region.