The Engesa EE-T1 Osório was a Brazilianmain battle tank prototype. It was developed as a privately funded venture by Engesa, with little government support. It was intended to be sold first to Arab and other Third World countries, jump-starting production — and enabling the Brazilian Army to later place its own orders without having to fund development costs. However macro-political events including the Gulf War and North American political pressure led to the tank's demise, and the tank was never acquired by the Brazilian Army.
Development started in 1982 and the first prototype was completed in 1985.
The EE-T1 was considered for service with the Saudi Arabian Army. It was evaluated against the French AMX 40, the American M1 Abrams, and the British Challenger 1 and emerged as the winner. The Osorio was quite cheap and affordable while having better results in the trials than the other three MBTs. In September 1989, Saudi Arabia quietly opted for the M1 Abrams instead and only announced its new decision shortly after Iraq invaded neighboring Kuwait, triggering the Persian Gulf War. The two unique prototypes were given to the Brazilian Army as a result of Engesa going bankrupt.