The aircraft then took off from Luanda, Angola, and landed at South Africa’s Waterkloof Air Force Base on April 24, the Defense Department said. (That day, flight records show an undisclosed stop, believed to be in South Africa.) The plane flew on to Harare, Zimbabwe, the next day.
The Russian Embassy had made a formal request to South Africa’s Foreign Ministry to let the plane land at the base, where diplomatic aircraft are allowed to travel, the Defense Department statement said. The statement did not specify what was in the diplomatic mail.
It is not unusual for countries to deliver diplomatic correspondence by aircraft, but such deliveries are open to abuse, said Kobus Marais, a member of South Africa’s main opposition party, the Democratic Alliance. Mr. Marais questioned why the plane did not use a commercial airport nearby, which is more typical for offloading diplomatic bags, he said.
Diplomatic mail could be as small as a few envelopes or as a large as a container, but a defense analyst, Helmoed Heitman, said it was unusual for Russia to use a cargo aircraft to deliver packages to its embassy.
The flight plan and landing were most likely influenced by Western sanctions, said Mr. Heitman. “They might have had a suspicion that if they land at a commercial airport, they might get arrested,” he said.
The plane is owned Aviacon Zitotrans, a Russian company, and it was one of the aircraft from the company hit by sanctions by the U.S. Treasury Department in January as part of sweeping measures against Russian entities, including Russia’s Wagner private mercenary company. Aviacon did not immediately respond to an email seeking comment.
The company has shipped military equipment around the world, including warheads and rockets, the Treasury Department said. The United States has also accused Aviacon of trying to use Turkish diplomats and a Turkish company to sell defense equipment on behalf of a Russian state-owned defense firm, Rosoboroneksport OAO.