The remarks come amid simmering tension between China and the United States and its allies and partners over flashpoints across East Asia, including Taiwan and the South China Sea, as well as broader economic rivalries under President Donald Trump.
Formally opening the Beijing Xiangshan Forum on security, Dong Jun said the world was "at another crossroads: peace or war, dialogue or confrontation" overshadowed by Cold War thinking, hegemony and protectionism.
"External military interference, seeking spheres of influence and coercing others to take sides will bring the international community into chaos," Dong added.
His remarks took veiled swipes at the United States and appeared more hawkish than his speech at last year's forum, particularly on topics such as tension over the democratically-governed island of Taiwan.
"An obsession with absolute superiority in military strength and a 'might is right' approach will lead to a divided world defined by the rule of the jungle and disorder," Dong said.
A strong Chinese military would be a force for peace, he added.
Dong's remarks follow recent speeches by President Xi Jinping against "hegemonism and power politics" and this month's large military parade in Beijing that showed off a host of new weapons.
Echoing Dong's warning, Singapore's Defence Minister Chan Chun Sing said an erosion of shared values meant "We again risk falling into a similar vicious cycle" of economic upheaval and radical politics that led to World War II.
While saying China was open to doing its part to uphold the international order, Dong added the People's Liberation Army would never allow any Taiwan "separatist" attempts to succeed.
"The return of Taiwan to China is an integral part of the postwar international order," he said, adding that it was ready "to thwart external military interference at all times".
China claims Taiwan as its territory and has never renounced the use of force to seize it.
Taiwan's President Lai Ching-te and his government strongly object to China's sovereignty claims, saying it is up to the island's people to decide their own future.
The forum, of about 1800 officials, military personnel and scholars from 100 countries, comes amid a flurry of diplomacy between the Washington and Beijing ahead of a possible summit of their leaders later in the year.
Dong spoke to US defence secretary Pete Hegseth by phone last week in their first direct exchange while Xi and Trump are expected to speak by telephone on Friday.
Diplomats and analysts say there is no clear sign yet of deeper military-to-military engagement, amid roiling regional tension, however.
"I just don't think that China understands the United States is no longer going to purchase a defence relationship by (being) accommodating," security analyst and former Pentagon official Chad Sbragia said on the sidelines of the event.
Most Western nations, including the US, have sent relatively low-level diplomatic representatives, with some saying they seek to learn more about China's military build-up and opaque military leadership.
with DPA
