CARACAS, Venezuela — President Nicolás Maduro said his government had captured two American “mercenaries” Monday in a murky operation allegedly intended to infiltrate Venezuela, incite rebellion and apprehend its leaders, adding a fresh complication to escalating tensions between Washington and Caracas. The socialist leader said the plan was to kill him.

In a lengthy speech Monday night, Maduro decried an ongoing “terrorist” assault on Venezuela that he said had led him to dispatch 25,000 reservists to the coasts. He displayed images that apparently depicted the two apprehended Americans in a lineup, one of them forced to lower his head by a captor.

U.S. officials and the mainstream Venezuelan opposition headed by Juan Guaidó have strongly denied any connection with the operation, which allegedly involved several dozen men, most of them defectors from the Venezuelan military who had been living hand-to-mouth in camps in Colombia. Former Venezuelan National Guard officer Javier Nieto Quintero and former U.S. Army Green Beret Jordan Goudreau, head of a Florida company that says it offers paid strategic security services, released a video Sunday announcing the start of “Operation Gideon” and calling on Venezuelan soldiers to join them.

Goudreau, in an interview with The Washington Post, confirmed that two Americans in what he says was a force of about 60 men were captured Monday along with six Venezuelans. He identified the Americans as Airan Berry and Luke Denman. Also captured was one of the operation’s leaders, former Capt. Antonio Sequea.

The Americans, Goudreau said, were fellow former Special Forces members he had known for years who had joined the operation as “supervisors.” He said he has engaged a lawyer in Venezuela and was reaching out to the State Department to try to secure their release.

Goudreau, who went public with the operation Sunday, said he provided false information to try to protect operatives still in harm’s way. He said Sunday that his forces had already entered Venezuela by land and sea.

But Monday, he said that Berry and Denman had been in a boat off Venezuela’s Caribbean coast on Sunday when Maduro’s government intercepted another of the operation’s vessels. He confirmed the Maduro government’s claim Sunday that eight people were killed and two captured by Venezuelan forces, which apparently had been tipped off to their arrival.

Goudreau said the Americans, along with six former Venezuela military men, spent Sunday night at sea. They were running out of gas, and Goudreau was trying to secure a vessel out of Aruba to “extract” them, he said. He said he last spoke to the crew around noon on Monday before learning of their capture.

The U.S. government “should engage and try to get these guys back,” Goudreau said. “They are Americans. They are ex-Green Berets. Come on.”

U.S. officials — who have indicted Maduro on narcoterrorism charges, offered a $15 million bounty for information leading to his capture or conviction, and imposed severe sanctions on his government — would not comment on the alleged arrests. U.S. officials have distanced themselves from Sunday’s operation and questioned its veracity and legality.

Colombian authorities and the mainstream opposition headed by Guaidó — the National Assembly president recognized as Venezuela’s rightful leader by the United States and more than 50 other nations — have said they believe the operation was infiltrated by Maduro loyalists. Maduro’s senior officials spoke of the planned operation for weeks before it was sprung Sunday.

“I don’t think all the people involved in this were working for the dictatorship,” said one senior opposition official, who spoke on the condition of anonymity to discuss internal matters. “I think most were trying to do something for the right reasons, but at an important level, this was leaked.”

Maduro suggested as much on Monday.

“We knew everything,” he said. “What they ate, what they didn’t eat. What they drank. Who financed them. We know that the U.S. government delegated this as a [U.S. Drug Enforcement Administration] operation.”

The DEA on Monday denied any involvement in the operation.

The senior opposition official said he had “high certainty” that the two Americans had indeed been captured. Guaidó released a statement Monday demanding that Maduro “respect” the human rights of individuals “captured in the last hours.” He did not specifically mention the arrest of Americans.

Goudreau deployed to Iraq with Berry and Denman in 2010, according to an active-duty soldier who served with all three of them in 10th Special Forces Group but did not deploy with them. He spoke on the condition of anonymity because of the sensitivity of the issue.

While the 10th Group is headquartered in Colorado, the men served in its selective company, Charlie, within the Germany-based 1st Battalion, the soldier said. The company is responsible for direct-action counterterrorism missions with responsibility throughout Europe, but has deployed many times to Iraq and Afghanistan.

A woman who said she was a cousin of Berry said she had not heard about his capture. A voice message left for Denman’s listed number was not returned. Goudreau’s and Berry’s apparent involvement in the failed operation didn’t shock many Green Berets who knew them, the soldier said, but it was surprising that Denman, an easygoing type, took part.

The biggest surprise in the Green Beret community, the soldier said, was that anyone could be so confident in the mission.

Goudreau “clearly had it in his mind that ‘yeah, I can do this,’ ” the soldier said.

Maduro offered a folksy account of the capture, claiming that patriotic fishermen aided the operation against the “terrorists.” Maduro called Goudreau a “liar” and called out Washington for its silence: “The U.S. government still has not said a word about the terrorist incursion.”

One person familiar with events supplied The Post with photos allegedly taken by Maduro’s forces that appeared to show one of the captured Americans shirtless and lying on pavement, his arms tied behind his back.

Diosdado Cabello, a senior Maduro government official, tweeted a video that allegedly shows one of the Venezuelan men arrested Monday in Chuao, on the Caribbean coast. The man, identified as Adolfo Baduel, the son of a jailed military officer, responds to a uniformed interrogator in the back of a van. His hands are tied behind his back.

“They say that they work with advisers of the president of the United States,” Baduel says.

“Who is the president of the United States?” the interrogator asks.

“Donald Trump,” Baduel answers.

Faiola reported from Miami. Horton reported from Washington.