Some shipping fleets, particularly those from China, have defied the restrictions by “going dark” — disabling automated tracking systems — to pick up cargo in Iranian ports, according to commercial analysts and intelligence from the authorities in Israel, a foe of Iran.

Impact: American and Israeli intelligence agencies say Iran’s Islamic Revolutionary Guard Corps is deeply entwined with the country’s petrochemical industry. Undercutting the sanctions keeps funds flowing to the group and reduces pressure on Iran to return to talks about its nuclear program.

The Daily: In our latest episode, a national security reporter for The Times discusses what Iran can learn from North Korea about relations with the U.S.

China widens its surveillance sweep

Until recently, China had used a muscular combination of high-tech surveillance and manpower to monitor and subdue Muslim minorities in the western Xinjiang region.

Now it has expanded its digital dragnet to include people who don’t even live in Xinjiang or China.

Border authorities routinely install a secret app — called Fengcai — on phones belonging to tourists and visitors that gathers personal data, including text messages and contacts. It also checks whether the devices have photos, videos, audio files or documents that match a list of 73,000 items. They include everything from ISIS publications to a photo of the Dalai Lama.

How we know: A team of journalists from The New York Times and other publications examined the policing app used in the region and interviewed several people who crossed the Xinjiang border recently. We also asked researchers in Germany and the U.S. to analyze the app’s code.