Chavez has repeatedly accused Washington of plotting an invasion to destabilize his government, despite U.S. denials.
The alliance would mean "we can guarantee Venezuela's sovereignty, which is now threatened by the United States," Chavez told reporters shortly after his arrival in Moscow.
Chavez is in Russia to broker a number of deals involving weapons purchases, oil exploration and possibly the creation of a joint financial institution.
Welcoming Chavez at Meiendorf Castle, his residence outside Moscow, President Dmitry Medvedev said Russian-Venezuelan relations "are one of the key factors of security in the (South American) region."
It is the presidents' first meeting since Medvedev took office in May.