Washington and Beijing have verbally sparred over China's increasingly assertive approach in disputed maritime regions, including the South China Sea.
In recent months, Chinese vessels have engaged in a series of high-profile confrontations with Philippine ships in the waters, which Beijing claims almost in their entirety despite an international court ruling that its assertion has no legal basis.
Speaking to a small group of journalists including AFP at the Xiangshan forum, Chinese army Lieutenant General He Lei said: "We hope that the South China Sea will remain a sea of peace."
But, he said, "if the United States moves its pawns behind the scenes, if it pushes countries to the front line, or if the United States itself ends up on the front line, then we in the Chinese People's Liberation Army... will never have any patience".
"We in the Chinese People's Liberation Army will resolutely crush any foreign hostile encroachment on China's territorial, sovereign and maritime rights and interests with firm determination, staunch will, strong capability and effective means," He said.
On Wednesday, China and the Philippines held what they called "candid" talks on South China Sea issues, in particular over a disputed reef that has become a hotspot for recent bilateral clashes.
"Both sides agreed to continue discussions on areas of cooperation, especially on hotline mechanisms, coast guard cooperation, and marine scientific and technological cooperation," a readout from the Philippine foreign ministry said.
'Win-win cooperation'
And on Thursday, Lieutenant General He said a resolution to tensions between Beijing and Washington over the issue "depends on the United States".
He also confirmed that US Deputy Assistant Secretary of Defense Michael Chase would attend this week's Xiangshan forum in Beijing.
"I hope that during his visit, during his meetings here, Michael Chase will listen more to the voices of China and the Chinese military," he said.
"The message we are sending to the United States is that we want the two countries and armies to be partners, to be friends, we want to pursue China-US relations featuring win-win cooperation," he said.
"We want the United States to make more contributions to regional and world peace, security and stability," he added.
Scores of delegates were in the Chinese capital Thursday for the Xiangshan forum, dubbed China's answer to Singapore's annual "Shangri-La" meeting.
It is set to host more than 500 representatives from over 90 countries and international organisations, organisers have said.
Official speeches are expected on Friday, when the forum's opening ceremony will take place and top military representatives from Russia, Pakistan, Singapore, Iran, Germany and others will participate in roundtable discussion.
