i thnk it was obvious from twitter post
destination is listed as vladivostok , russian port from where akula was leased.
India is reportedly expected to sign a $3bn deal with Russia later this week to lease another Akula-class submarine for use by the Indian Navy.
www.naval-technology.com
The lease for Chakra II is set to expire in 2022. The report added that India is likely to seek an extension of the lease for a further five-year period to keep the vessel in service until the construction and testing of its successor has been completed.
article says lease not yet expired , so maybe maintenance/ retrofitting / repairs ??