The United States deepened its dispute with Venezuela on Monday, blocking the U.S. assets and property of seven Venezuelan officials, prohibiting Americans from doing business with them and barring them from U.S. entry.

The new sanctions, imposed by an executive order signed by President Obama, were the second round since Congress passed authorizing legislation in December after opposition arrests and human-rights abuses in Venezuela during antigovernment protests. Several dozen Venezuelans were barred last month from obtaining U.S. visas on human-rights and public corruption grounds.

Late last month, Venezuelan President Nicolas Maduro, who has accused the United States of plotting to overthrow his government, ordered a sharp cut in the number of diplomats at the U.S. Embassy in Caracas.

The individuals on the new U.S. list, most of them top security officials, do not include Maduro or the National Assembly president, Diosdado Cabello, the country's second-most-powerful figure, who has strong ties to Venezuela's military and security forces.

Maduro has cast U.S. sanctions targeting specific individuals in his government as a kind of collective punishment for all Venezuelans. With Maduro's popularity near an all-time low, fewer Venezuelans appear willing to go along with his attempts to blame the United States for the country's problems.

At a rally after the sanctions announcement, Cabello said that when the Americans "talk about threats, that means bombing." The U.S. goal, he said, is to topple the government before a hemispheric summit to be attended by Obama next month.

The state-run news agency called the sanctions "a new escalation of aggression against Venezuelan sovereignty and democracy" and noted that Obama's executive order had declared the situation there "an unusual and extraordinary threat to the national security and foreign policy of the United States."

U.S. Treasury officials said that is boilerplate language, required by decades-old authorizing legislation and contained in dozens of sanctions orders applying to other countries.

But many in Venezuela - and not only within the government - appeared to interpret the "national security threat" designation as an escalation of the Obama administration's challenge to Maduro.

"Obama declares Venezuela a threat to national security," read a headline in El Nacional, one of the country's last remaining opposition newspapers.

The designation may help Maduro's attempt to depict Venezuela's domestic crisis as an international confrontation with a "meddling" and "imperialist" foe, said Michael Shifter, president of Inter-American Dialogue, a Washington-based think tank.

"Washington's frustration is understandable, and the situation in Venezuela is awful and getting worse, but it is hard to see what ratcheting up the rhetoric will actually accomplish," Shifter said. "The language does not correspond to the means Washington is prepared to use in these circumstances."

A senior administration official suggested that Obama's opening to Cuba may help convince other Latin American countries that Venezuela deserves isolation.