A few key reasons contributed to this decision:
1. Nuclear Monopoly and Strategic Advantage: The United States and the Soviet Union dominated the nuclear landscape, with America initially holding the upper hand. Maintaining this monopoly meant having greater leverage and power in international affairs and deterrence against potential adversaries. Sharing nuclear secrets would diminish this dominance and weaken the US's global influence.
2. Fear of Nuclear Proliferation: Post World War II, there were concerns about the potential spread of nuclear weapons to other nations. The US wanted to prevent the emergence of additional nuclear powers that could disrupt the balance of global power and stability, fearing the potential for conflicts or even nuclear warfare.
3. Security and Safeguarding: Sharing nuclear secrets involves disclosing highly classified and sensitive information, which posed enormous security concerns. These secrets encompassed intricate details of nuclear weapons design, production, materials, and technology. Given the complexities of nuclear engineering, there was apprehension that sharing these secrets might lead to unauthorized access, potential misuse, or the replication of nuclear weapons by other countries.
4. Diplomatic Tensions: During the Cold War, the US and the Soviet Union were rivals in a tense geopolitical standoff. America worried that sharing nuclear technology could potentially benefit its adversaries or strengthen the Soviet Union's nuclear capabilities, thus undermining America's deterrence strategy and upsetting the balance of power.
5. Nonproliferation Objectives: The US aimed to promote nonproliferation efforts and encourage peaceful uses of nuclear energy. By tightly controlling nuclear secrets, America could exercise influence over the international community and set stringent conditions for nations seeking nuclear cooperation, thereby minimizing the risk of weaponization.
Eventually, the United States shifted its approach to nonproliferation and nuclear sharing, but the initial refusal to share secrets stemmed from a combination of strategic considerations, security concerns, and the objective of maintaining a cautious approach to the spread of nuclear knowledge and technology.