the U.S. proposed that Brazil abandon the sensitive part of its nuclear deal with Bonn in exchange for a package of substantial economic aid and nuclear assistance from Washington. The two countries reached an informal agreement that would lead to further confidential negotiations. Amidst Geisel's decision, Brazil was beginning to experience an economic crisis. Additionally, the implementation of the nuclear plan with Bonn had some technical difficulties and the possibility loomed of West Germany diluting certain elements of the treaty in accordance with U.S. wishes. Nonetheless, Geisel asked Robinson to keep this agreement secret, as a way to avoid domestic criticisms coming from the military hardliners and the Brazilian public, which supported "national nuclear independence." The U.S. presidential election in November 1976 saw Ford's defeat by challenger Jimmy Carter, the latter having adopted a different approach to nuclear cooperation. Ahead of Carter's January 1977 inauguration, the Geisel administration indicated during meetings with Carter's transition team that Brazil was willing to renounce nuclear sensitive technologies. U.S. officials knew that a key aspect for the acceptance of an indefinite deferral of the sensitive aspects of the nuclear project was "to convince Brazil of the durability of its fuel supply." However, a problem occurred when an off-the-record comment by Joseph Nye, then Carter's Assistant Secretary of State for nuclear affairs, was reproduced in a newspaper article. Nye had stated that Brazil and West Germany would renounce the transfer of sensitive nuclear technology, such as enrichment and reprocessing plants, in exchange for the guarantee of nuclear fuel deliveries to Brazil. Hardliners within Brazil's military regime strongly opposed those terms, which led the government to reject the U.S. proposal and harden its anti-NPT stance. After the end of military rule in 1985, a new Constitution was approved in 1988 that remains in force today. The document affirms that "all nuclear activity within the national territory shall only be admitted for peaceful purposes and subject to the approval of the National Congress." The international community did not view this language as a reassurance, as the wording could be construed as an endorsement of PNEs. Elected president by popular vote in 1989, Fernando Collor voiced his opposition to nuclear weapons and rejected the idea of Brazil ever conducting PNEs. In a public rebuke of the military's nuclear activities, Collor held a ceremony in September 1990 to seal shut the nuclear explosive test shafts at the Air Force