Washington has expressed concern over the signing of a controversial arms deal between Venezuela and Spain.
Venezuela said the equipment would help border security
The US State Department said it was assessing whether there was US protected technology in the equipment.
Under the $2bn deal, Spain will supply eight navy patrol boats and 12 military transport planes to Venezuela.
The US had tried to block the signing saying that the Venezuelan President, Hugo Chavez, was a source of instability in the region.
But both Venezuela and Spain insisted the equipment was for peaceful purposes.
Mr Chavez said that the boats and planes would be used to combat the drug-trafficking on the Venezuelan-Colombian border.
As he signed the deal in Caracas with Spain's Defence Minister Jose Bono, he accused Washington of trying to impose its will on the world.
"There may be some issues related to the fact that there would be US technology included in some of the equipment," the US State Department spokesman Sean McCormack told reporters in Washington.
He added that the US was "working through those issues" and that "there has not been any final conclusion on that question yet".
The arms deal was agreed during Spanish Prime Minister Jose Luis Rodriguez Zapatero's two-day visit to Venezuela last March.
Tensions between Washington and Caracas have grown in recent months, in part because of US criticism over Venezuela's purchases of military equipment.
Earlier this year, the South American country signed deals for Brazilian aircraft and for Russian automatic rifles and helicopters.