The Iranian Navy unveiled two new submarines and two missile-launching warships on Wednesday, Mehr news agency reported.
The two domestically-built Ghadir submarines and the Sina-7 warships - together with two repaired hovercrafts - officially joined the Iranian Navy, Mehr quoted navy commander Habibollah Sayari as saying.
Iran said in June that it would use its nuclear technology know-how to design nuclear-powered submarines, which could enable the navy to have a constant presence in free waters as well as long-distance operations.
In 1996, Russia provided Iran with diesel-electric submarines, which at that time made it the only state in the Gulf with submarines. Iran started the production of its own submarines in 2008 and delivered four new types to the navy in August 2010.
The submarines have caused concern in the United States and the West, which considers them a threat to the strategic balance in the volatile Gulf region.
Iran claims to have become self-sufficient in manufacturing all types of military vessels, but insists it would use its military strength only for safeguarding peace and security in the Gulf and the Gulf of Oman.