Two Russian military planes landed in Venezuela's main airport on Saturday, reportedly carrying dozens of troops and large amounts of equipment.
The planes were sent to "fulfil technical military contracts", Russia's Sputnik news agency reported.
Javier Mayorca, a Venezuelan journalist, wrote on Twitter that he saw about 100 troops and 35 tonnes of equipment offloaded from the planes.
It comes three months after the two nations held joint military exercises.
Russia has long been an ally of Venezuela, lending the South American nation billions of dollars and backing its oil industry and military. Russia has also vocally opposed moves from the US to sanction the government of Venezuelan president Nicolás Maduro.
Mr Mayorca said on Twitter that a Russian air force Antonov-124 cargo plane and a smaller jet landed near Caracas on Saturday.
He said that Russian General Vasily Tonkoshkurov led the troops off one of the planes.
A military plane with a Russian flag on its fuselage could be seen on the tarmac at an airport on Sunday. Images on social media also appeared to show Russian troops gathered at the airport.