Navy chief Admiral Sunil Lanba on Friday said it is odd for China to deploy submarines for anti-piracy operations in the Indian Ocean and added that India has also carried out a threat assessment.Chinese submarines have been spotted in the Indian Ocean region repeatedly and China has claimed they were to assist in anti-piracy operations.Addressing the annual press conference ahead of Navy day, Admiral Lanba said Chinese PLAN submarines had been regularly visiting the Indian Ocean since 2013 and there were two deployments alternately - a conventional submarine and a nuclear propelled submarine."They may say it is for anti-piracy operations but it is an odd task to give to a submarine."He said a submarine was not a suitable platform for anti-piracy operations and that India had carried out a threat assessment."When you have submarines in your area, you do carry out threat assessment... So we did carry out a threat assessment," he said.He added that Chinese Naval ships had been coming to the Indian Ocean since 2008.At one point in August this year, he said at least 14 Chinese Naval ships were present in the Indian Ocean.