WASHINGTON — For the past month, the Navy cruiser San Jacinto had sailed off the West African island nation of Cape Verde on a secret mission aimed at helping deal a major blow to President Nicolás Maduro of Venezuela, an avowed adversary of the Trump administration.

The mission was set in motion in early June, when Alex Saab, a Colombian businessman who is widely believed to be the architect of the economic deals that are keeping the Maduro government afloat, was arrested in Cape Verde when his private plane stopped to refuel en route to Iran from Venezuela. The United States sought his extradition under American money laundering charges, and judicial proceedings began.

“Saab is critically important to Maduro because he has been the Maduro family’s frontman for years,” said Moises Rendon, a Venezuela specialist at the Center for Strategic and International Studies in Washington. “Saab has access to privileged information to Maduro’s corruption schemes in and outside Venezuela.”

The subsequent stealthy arrival of the American warship coincided with President Trump’s firing of Defense Secretary Mark T. Esper in early November. For months, Mr. Esper had fended off pleas from the State and Justice Departments to deploy a Navy vessel to Cape Verde to deter Venezuela and Iran from plotting to spirit Mr. Saab away from the island. Mr. Esper scoffed at concerns over a cloak-and-dagger jailbreak, and said sending in the Navy was a misuse of American military might. A Coast Guard cutter was dispatched in August instead.

With Mr. Esper out of the way, however, his replacement, Acting Defense Secretary Christopher C. Miller, a former White House counterterrorism aide, quickly approved the San Jacinto’s deployment from Norfolk, Va. The ship sailed across the Atlantic to keep a close eye on the lone captive.

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In the waning days of Mr. Trump’s term, the tale of the San Jacinto and its unlikely monthlong mission illustrates what critics say is the administration’s capricious use of the armed forces — deploying troops to the southwestern border one day, yanking other troops abruptly from northeast Syria the next.

It is also the latest effect of Mr. Trump’s purge of the Pentagon’s top leadership and his installment of largely hard-line loyalists. With Mr. Esper gone, Mr. Miller has ordered deeper troop cuts in Afghanistan, Iraq and Somalia; ousted the policy official overseeing the military’s efforts to combat the Islamic State; and considered pulling back military support for the C.I.A., including its drone fleet.

The showdown over Mr. Saab is the latest twist in the tense relationship between the United States and Venezuela. In 2017, Mr. Trump said he would not rule out a “military option” to quell the chaos in Venezuela. In 2018, the Trump administration held secret meetings with rebellious military officers from Venezuela to discuss their plans to overthrow Mr. Maduro.
ImageSupporters of President Nicolás Maduro of Venezuela this month in Caracas.
Supporters of President Nicolás Maduro of Venezuela this month in Caracas.Credit…Matias Delacroix/Associated Press

And in August, the United States seized more than 1.1 million barrels of Iranian fuel that was headed to Venezuela in a high-seas handover that blocked two diplomatic adversaries from evading American economic sanctions.

So it came as no surprise that administration aides were elated when officials in Cape Verde arrested Mr. Saab on his fuel stop, responding to a wanted alert from Interpol known as a red notice, which had been in effect because of the American money laundering charges.
The New York Times