Singapore Foreign Affairs Minister K. Shanmugam said a strong United States-Japan alliance is in the interest of China and the rest of the world.
Delivering a speech on the geopolitics of East Asia at the American Jewish Committee Global Forum in Washington, Mr Shanmugam said a weak alliance might push Japan towards nuclear weapons.
"If the alliance is weakened, Japan may well eventually have to reconsider its steadfast disavowal of nuclear capabilities."
"Thus, in an ironic way, it is in China's, as well as everyone else's interests that Japan feels secure about the US-Japan alliance," he said, addressing concerns about the relationship between Tokyo, Beijing and Washington.
"A nervous, technologically advanced Japan, facing a nuclear-armed China, is certainly not the best scenario for the US or for regional stability," he added.
Mr Shanmugam's comments come amid rising China-Japan tensions, particularly over the islands in the South China Sea, which the Japanese call Senkaku and the Chinese call Diaoyu.
Despite these disputes, Mr Shanmugam said China and Japan need each other: "Japan needs China's market; while China needs Japanese investments."
A "new model of great power relations is urgently required" between the two nations, the minister said, noting that both have hierarchical societies and have almost never treated each other as equals.
Turning to Asean, Mr Shanmugam said the rise of China requires the regional grouping to "rethink existing paradigms".
He said Asean, with Singapore well-positioned as its hub, offers tremendous opportunities as it requires an increasing number of goods, energy, food and services.
But it also has to juggle two global powers - China and the US.
"It remains mindful that both powers do not always have common interests, and both may view their relationship at a different level," said Mr Shanmugam.
The Singapore minister is on a week-long visit to the US capital.