IMPHAL, January 20: Imphal East commandos conducted a combing operation at J.N. Hospital and the surrounding areas of Porompat today from 5.30 a.m. to 7.30 a.m. as a precautionary measure in the run up to the Republic Day function to be held on 26 January. During the operation, 15 persons were picked up for questioning and verifications but all of them turned out to be civilians reportedly.