Russia has rejected claims the operation is aimed at "third countries"
The Venezuelan and Russian navies have begun joint exercises in the Caribbean Sea, close to US territorial waters.
The three-day operation marks the first time that the Russian fleet has been in the area since the end of the Cold War.
The Russian navy says it will include anti-aircraft defence, and tactics to combat terrorism and drug-trafficking.
Russian President Dmitry Medvedev recently completed a tour of Latin America that was intended to strengthen his country's influence in the region.
Last week, he and Venezuelan President Hugo Chavez signed a deal to promote the development of nuclear energy for civilian use.
Balance of power
About 1,600 Russian and 700 Venezuelan sailors on four Russian ships and 12 Venezuelan vessels are expected to participate in the VenRus 2008 joint exercise in neutral waters over the next three days.
The Russian ships, led by the missile cruiser Peter the Great and three support vessels, left the port of La Guaira at dawn on Monday along with three Venezuelan frigates.
Russian President Dmitry Medvedev just completed a tour of Latin America
Ahead of the operation, Venezuelan and Russian officials rejected suggestions that they were aimed at "third countries".
"This series of exercises aims to evaluate the skills and capabilities of the fleets of both nations to fight against terrorism and drug-trafficking," said Russian Vice-Admiral Vladimir Korolev, deputy commander of the Northern Fleet.
US Secretary of State Condoleezza Rice has also dismissed the impact of the Russian naval deployment.
"A few Russian ships [are] not going to change the balance of power," she said.
Correspondents say Washington has been concerned by major arms deals between Russia and Venezuela since 2005, which have totalled some $4.4bn (£2.39bn).