 The Japanese attack on Pearl Harbor in December 1941 brought the United States into the war . In the following months , the Japanese advanced in Southeast Asia , and the British Cabinet sent a mission led by Sir Stafford Cripps to try to conciliate the Indians and cause them to fully back the war . Cripps proposed giving some provinces what was dubbed the " local option " to remain outside of an Indian central government either for a period of time or permanently , to become dominions on their own or be part of another confederation . The Muslim League was far from certain of winning the legislative votes that would be required for mixed provinces such as Bengal and Punjab to secede , and Jinnah rejected the proposals as not sufficiently recognising Pakistan 's right to exist . The Congress also rejected the Cripps plan , demanding immediate concessions which Cripps was not prepared to give . Despite the rejection , Jinnah and the League saw the Cripps proposal as recognising Pakistan in principle . 
