The head of the US National Security Agency, Admiral Michael Rogers said the arms could fall into the hands of pro-Maduro civilian groups.
"Venezuela's unpopular, autocratic government will turn to increasingly repressive means to contain political opponents and street unrest," National Intelligence Director Dan Coats told the Senate Intelligence Committee.
He was providing an overview of the intelligence community's annual "Worldwide Threat Assessment," which was released Thursday, laying out the risks to national security.
Venezuela has been wracked by more than a month of violent anti-government street protests that have killed nearly 40 people and left hundreds injured and arrested.
Opposition forces are calling for the removal of President Nicolas Maduro, blaming him for an economic crisis that has saddled the oil-rich country with major shortages of food, medicine and other basic goods.
The head of the US National Security Agency, Admiral Michael Rogers, also testified before the intelligence committee, expressing concern about a flow of arms into Venezuela that he said could fall into the hands of pro-Maduro civilian groups.
"There are plenty of weapons running around there and the risk is real, serious, and ultimately a threat to South and Central America."
In Cuba, which is preparing for a historic transition to an era without a Castro in power at the beginning of next year, the government will focus on maintaining political control while managing a recession, Coats told the panel.
The country's GDP fell 0.9 percent last year, driven by the crisis in its ally Venezuela.