Sean McCormack, the US state department spokesman, said on Friday that Washington had told Venezuela by diplomatic note that it was declaring Jenny Figueredo Frias, a minister counsellor at the embassy in Washington, persona non grata.
McCormack said: "This decision is in response to the government of Venezuela's decision to yesterday expel Commander John Correa, US naval attache in the US embassy in Caracas."
McCormack said Figueredo, the chief of staff to Venezuela's ambassador, had 72 hours to leave. He did not accuse her of anything but said simply that she was "the most appropriate" choice for expulsion.
"We don't like to get into tit-for-tat games like this with the Venezuelan government, but they initiated this and we were forced to respond," McCormack said.
Pavel Rondon, the vice-foreign minister of Venezuela, told Union Radio in Caracas that America's action was "incongruous and disproportionate".
Mari Pili Hernandez, Caracas's vice foreign minister for North America, said Figueredo was a "model" diplomat and called her expulsion a "reprisal of a political character".
"The decisions that Venezuela take are taken based on facts and proof, not simply for retaliation"
Mari Pili Hernandez, Venezuelan vice-foreign minister for North America
But Venezuela would not follow Washington's move with the expulsion of a second US diplomat, she said.
"The decisions that Venezuela take are taken based on facts and proof, not simply for retaliation," Hernandez said.
Despite the diplomatic row, Venezuela has continued to expand its subsidised oil programme to help the poor and needy underclass of the US.
Donations to Vermont will begin on Tuesday. Bernie Sanders, an independent Vermont representative who is running for the Senate, said in a statement that Venezuela was giving 2.4 million gallons of heating oil at a 40% discounts to households qualifying for state heating assistance.
A further 108,000 gallons will be distributed free of charge to homeless shelters.
Vermont is the sixth state to receive cheap oil from Venezuela, after shipments to Massachusetts and New York in November, and Maine, Rhode Island and Pennsylvania in January.