Complex sentence: The September 1944 Hyde Park Agreement extended both commercial and military cooperation into the post-war period, and the British government had trusted that America would continue to share nuclear technology, which it considered to be a joint discovery.
Split into simpler sentences: The September 1944 Hyde Park Agreement extended both commercial and military cooperation into the post-war period. The British government had trusted that America would continue to share nuclear technology, which it considered to be a joint discovery.