Argentina, following an alert from America and other countries, is holding at its airport in Buenos Aires an Iranian cargo plane and its crew of Iranian and Venezuelan nationals over suspected terrorist activity.

The move comes as Iran’s terrorism infiltration of the Western Hemisphere is emerging as a top concern for the government of Argentina. Worried about the suspiciously large crew of the cargo plane and other oddities, it has confiscated the crew’s passports and, last night, seized their cell phones and other electronic equipment. 

The high alert might also be related to the notorious bombing in 1994 of the Jewish center at Buenos Aires, a terror attack that claimed 86 lives and has been linked by Argentinian investigators to Iran. In 2015, the prosecutor who made that allegation, Alberto Nisman, was murdered a day before he was due publicly to accuse the then-presdient of Argentina, Cristina Kirchner, of covering up Iran’s role in the attack.

So the pressure is on in the current drama. Can a government that swept Iran’s past sins under the rug and still has ties with Tehran change its spots this time? The story has led the news in the Argentine press for days.

The cargo plane, a Boeing 747 Dreamliner registered to the Venezuelan airline Emtrasur but likely owned by Iran, landed in Argentina June 6. It tried to leave two days later, but after Uruguay, Paraguay, and possibly Brazil denied entry to their airspace, it eventually returned to Argentina. Since then it has been held at Buenos Aires’s Ezeiza airport.

“Information was received through different channels from foreign organizations, warning that members of the crew belonged to companies connected to the Quds force of the Revolutionary Guard of Iran,” the Argentinian defense minister, Aníbal Fernández, said. 

Buenos Aires was under pressure from America, Israel, and several of its neighbors to investigate the plane. Its seemingly benign cargo, including cigarette cartons, is suspected of being a cover for terrorist recruitment activities, as the crew, consisting of seven Iranian nationals and 11 Venezuelans, seems to care little about loading and unloading of the merchandise aboard.

The plane’s captain, Gholamreza Ghasemi, is a board member of the Iranian airline Qeshm Fars Air, which is under American sanctions for its role in transporting illicit arms to and from Syria on behalf of the Islamic Revolutionary Guards Corps. Mr. Ghasemi’s name is similar to that of a sanctioned top IRGC official, though the connection could not be confirmed.

A senior fellow at the Foundation for the Defense of Democracies, Emanuele Ottolenghi, who has been monitoring terrorism in Latin America for years, tells the Sun that the plane’s crew “is no less important than its cargo.”

Suspicions arose for several reasons, Mr. Ottolenghi says. The size of the crew is much larger than the handful of people that normally operate cargo planes. Stopovers the aircraft has made during its flights lasted days, rather than hours, as is normal with cargo planes.

Then there are the plane’s odd destinations. Its initial test flight was in Iran in January. In February it flew to Minsk, Belarus, and from there to Caracas on its maiden journey. It then continued to West Africa, Russia, Pakistan, Hong Kong, Nicaragua, and Cuba. Other stops included Tehran, Caracas, and Ciudad Del Este, which abuts the crime- and terrorist-plagued tri-state area between Paraguay, Argentina, and Brazil.

Suspicions were further raised as the plane frequently disappeared from radar coverage, possibly after the crew illegally shut down its transponder. “It is possible that the flights and merchandise transported are a cover for regime officials to spend time on the ground and meet assets,” Mr. Ottolenghi said. 

Many Argentines remember how Iranian asset-cultivation led to the 1992 bombing of the Israeli embassy at Buenos Aires and the 1994 attack on the Jewish community center there, known as AMIA. The AMIA bombing, which killed 86 people, was the largest terrorist event in the country’s history.  

A federal Argentine prosecutor, Cecilia Incardona, yesterday demanded that Judge Federico Villena open an official investigation, and called on him to lift a gag order he had earlier imposed over the investigation.

She argued that as a terrorism victim, Argentina’s Jewish community, represented by an umbrella organization, Delegación de Asociaciones Israelitas Argentinas, has a right to access court files and evidentiary findings. DAIA has “a legitimate interest in the investigation,” Ms. Incardona said, according to Argentina’s top newspaper, La Nacion.

In 2015, Nisman, the top investigator of the AMIA bombing, was found dead in his Buenos Aires apartment one day before a scheduled appearance before congress. There, Nisman planned to present evidence of ties between Iran and the government of the president at the time, Cristina Kirchner.

Suspicion that Nisman’s death was not a suicide, as the government argued at the time, but a murder committed by Iran, the Argentinian government, or both, have haunted Ms. Kirchner ever since. The current president, Alberto Fernandez, is a close ally of Ms. Kirchner. 

It is possible that Tehran could reach out to Ms. Kirchner, over whom the Iranians still have influence, Mr. Ottolenghi says. Yet, he adds, “up until now it hasn’t worked.” American leverage over Buenos Aires and internal political pressures might well this time force Argentinia’s most Iran-friendly government to clamp down on terrorism.