'Bluebird' was a US unrealised plan for amphibious landings against the Japanese forces on the island of Formosa and on the coast of China along the South China Sea, with elements of the plan, which was to have been implemented in March 1945, later revived for active and effective use as part of the deception scheme for the 'Detachment' assault on Iwo Jima (November 1944/June 1945).

Developed by Captain Percival McDowell of the US Navy, 'Bluebird' lacked this formal designation until 12 January 1945, possessed no explicit object in terms of desired Japanese action, but was created to 'convince the enemy of [the US] intention of invading the Island of Formosa and the south coast of China between Formosa and Hainan Island in the spring of 1945, and to continue this threat through the summer of 1945, if, and as, necessary.' Implied in this concept was, of course, the desirability of inducing the Japanese to deploy forces to meet such a threat rather than to tackle the actual planned 'Iceberg' and 'Detachment' undertakings against the islands of Iwo Jima and Okinawa respectively.

The basic plan was approved by the Joint Chiefs-of-Staff Committee on 30 December 1944, and was based on a 'story' that US forces would make an amphibious assault on either the island of Formosa or the coast of southern China, with D-day set for 1 April 1945, as the means of reducing the Japanese pressure on China, secure bases near or on the Asian mainland for further operations and the blockade of Japan, seize the China coast from Hong Kong to Amoy and thereby to open overland supply routes to nourish the forces of the Chinese nationalist forces of Generalissimo Chiang Kai-shek, and isolate the Japanese forces in South-East Asia and the East Indies.

After General Douglas MacArthur had launched his January 1945 'Mike I' invasion of Luzon island in the Philippine islands group, D-day for 'Bluebird' was to be postponed to 20 April on the supposed grounds of reverses in Philippine operations and logistical difficulties.

The largest and most elaborate all-US deception yet attempted, 'Bluebird' was implemented through deceptive communications, operations and administrative arrangements, and 'special means'. 'Bluebird' was itself supported by the separate 'Sturgeon' and 'Valentine' deception operations.

'Bluebird' and its two supporting components was of considerable importance to the Allies, for it gradually persuaded the Japanese to make irrelevant deployments of their available strength: at the start of 'Bluebird' the Japanese had some 67,000 men in southern China, 85,000 men on Formosa, and 70,000 men on Okinawa, but by the time 'Detachment' was launched on 1 April 1945, the first two of these strengths had been changed to 161,000 and 240,000 respectively, while that on Okinawa remained unaltered at 70,000.