The Quadrilateral Security Dialogue (QSD) was an informal strategic dialogue between the United States, Japan, Australia and India that was maintained by talks between member countries. The dialogue was initiated in 2007 by Prime Minister Shinzo Abe of Japan, with the support of Vice President Dick Cheney of the US, Prime Minister John Howard of Australia and Prime Minister Manmohan Singh of India. The dialogue was paralleled by joint military exercises of an unprecedented scale, titled Exercise Malabar. The diplomatic and military arrangement was widely viewed as a response to increased Chinese economic and military power, and the Chinese government responded to the Quadrilateral dialogue by issuing formal diplomatic protests to its members.

In early 2007, Prime Minister Abe proposed the Quadrilateral Security Dialogue, or “Quadrilateral Initiative”, under which India would join a formal multilateral dialogue with Japan, the United States, and Australia.

The initiation of an American, Japanese, Australian and Indian defense arrangement, modeled on the concept of a Democratic Peace, has been credited to former Japanese Prime Minister Shinzo Abe. The Quadrilateral was supposed to establish an “Asian Arc of Democracy,” envisioned to ultimately include countries in central Asia, Mongolia, the Korean peninsula, and other countries in Southeast Asia: “virtually all the countries on China’s periphery, except for China itself.” This has led some critics, such as former U.S. State Department official Morton Abramowitz, to call the project “an anti-Chinese move,” while others have called it a “democratic challenge” to the projected Chinese century, mounted by Asian powers in coordination with the United States. While China has traditionally favored the Shanghai Cooperation Organisation, the Quadrilateral was viewed as an “Asian NATO;” Daniel Twining of Center for a New American Security (CNAS) has written that the arrangement “could lead to military conflict,” or could instead “lay an enduring foundation for peace” if China becomes a democratic leader in Asia.