(Bloomberg) – Iran’s oil exports are surging this month, swelling global flows at a time when other producers are cutting back, according to a firm that monitors satellite imagery of individual tankers.

The boom is awkward for the U.S., which officially still has sanctions in place that should restrict Iran’s shipments. Even so, the extra cargoes will help to cushion the impact of reductions by Saudi Arabia, Russia and other nations in the OPEC alliance.

TankerTrackers.com Inc., which provides data on oil cargo shipments to governments, insurers and other institutions, estimates that the Persian Gulf state exported 2.2 MMbpd of crude and condensates during the first 20 days of August. If maintained, it would far exceed any other month this year and is well above what other oil-shipping analytics firms say.

It was already known that Iran’s shipments were surging, but the data for August would represent a marked leg higher if maintained for the remainder of the period. The flow rate for the past 28 days show shipments running at a rate of 2.1 MMbpd.

Flows from the Persian Gulf country are notoriously hard to monitor because the large numbers of tankers sailing there will routinely switch off their transponders, making them invisible to systems that rely on collating the signals that vessels emit.

TankerTrackers studies images from satellites and collates data manually, meaning it doesn’t rely on those Automatic Identification System, or AIS, signals.

None of the exported barrels came from floating storage, although it’s possible some could have come from on-land tanks, TankerTrackers co-founder Samir Madani said.

The lion’s share of the August flow has been crude with just over 200,000 bpd of condensate — a lighter form of oil.

The Persian Gulf state is selling the vast majority of its bbl to China, as other past customers like South Korea and Japan steer clear of sanctioned bbl. India, previously a big buyer of Iranian oil, has pivoted to taking more Russian bbl.

Even as Iran has made steps to reconcile with its neighbors and deal with the U.S., tensions remain around shipping in the vital Strait of Hormuz waterway.

About a fifth of the world’s oil passes through the strait which lies at the mouth of the Gulf. Iran has harassed vessels and seized tankers in the area, and the U.S. recently increased its naval presence in the region.