The Alaed, the ship at the center of a recent diplomatic row between Russia and the West, arrived to St. Petersburg on Friday evening, according to the data from the AIS tracking system.
A security source said the ship had offloaded its cargo of Mi-25 attack helicopters it carried to Syria in the Russian port of Baltiysk in the Kaliningrad region earlier on Friday.
U.S Secretary of State Hillary Clinton accused Russia in June of supplying helicopter gunships to Damascus which could be used to massacre civilian demonstrators in the ongoing insurrection in the country. Russia said it was fulfilling a contract previously signed long ago for repair of the aircraft and denied they could be used for attacking civilians.
Femco, the shipping agent which owns the ship, the Alaed, previously said the documentation accompanying the cargo did not contain any data linking it to Syria.
The Alaed originally set sail from Baltiysk in June, allegedly carrying three Mi-25s and some air defense equipment. The ship turned back to Russia later that month, after its insurance cover was suspended by its British insurer, Standard Club. It later turned back and entered the port of Murmansk, and was later re-flagged as a Russian registered vessel.
The U.S. Congress voted to break off all contacts with Russia's state arms corporation Rosoboronexport on Thursday over concerns about Russia continuing to supply arms to Syria. Russia has maintained it is only fulfilling contracts signed before the current wave of unrest in Syria, and said last week it will not supply a batch of Yak-130 advanced jet trainers to Damascus.