Why couldn't the Indian National Army capture Imphal?

The Indian National Army was three kilometres from Imphal when the Japanese forces had to withdraw from the Indo-Burma border because of their entanglement with the Americans in the Pacific Ocean. The rainy season set in and Rangoon was recaptured by the British in May, 1945. The INA soldiers were disarmed and made prisoners of war. Hence, INA couldn't capture Imphal.