Russia has rejected US claims that a planned arms shipment to Venezuela may end up in Colombian rebel hands.
Mr Chavez (left) and Mr Putin are both keen on closer trade ties
The Russian foreign ministry described the American objections as groundless - it said the deal with Venezuela did not break international law.
On Thursday, the US State Department repeated long-standing concerns about the shipment of 100,000 automatic rifles and a number of helicopters.
It accused Venezuela of starting an arms race.
The Venezuelan ambassador to Russia, Carlos Mendoza Pottella, described such comments as absurd.
He said the country was simply replacing its obsolete weaponry.
Venezuela is also believed to be considering buying Russian MiG-29 fighter jets.
Not at war
Russian Foreign Minister Sergey Lavrov told journalists that the purchase did not violate any laws or any of Moscow's international obligations.
And a diplomatic source told Interfax news agency: "Russia, like any other state, has the right to develop military-technical co-operation with any country not under arms trade sanctions of the UN or other international organisations.
"As far as we know, Venezuela is not in a state of war or conflict with any Latin American country."
US State Department spokesman Adam Ereli said on Thursday that the weapons could have a "destabilising effect" on the region.
The US suspects Venezuelan President Hugo Chavez of being sympathetic to the Revolutionary Armed Forces of Colombia (Farc), the country's main left-wing rebel movement.
The South American neighbours have recently been involved in a dispute after Colombia admitted paying bounty hunters who had captured a Farc leader in Caracas.
Mr Chavez is due to meet Colombian President Alvaro Uribe on Tuesday to seek a resolution.