Shipping through the Strait of Hormuz has slowed to a crawl with most commercial traffic paralyzed, while a handful of Iranian-linked vessels continue to navigate the waterway despite escalating security risks.

An Iranian supertanker was spotted in the waters north of Hormuz on Sunday, with its destination listed as China, according to vessel-tracking data compiled by Bloomberg. A few more Iran-linked ships crossed through the chokepoint in the last 24 hours.

A US strike on military targets on Kharg Island, which handles most of Iran’s crude exports, has heightened risks in global oil supply chains. The US is also pressing allies to deploy warships to reopen the Strait of Hormuz.

At the same time, the successful passage of two Indian LPG tankers suggests that back-channel coordination may be allowing select vessels to bypass the current gridlock.

Electronic interference continues to disrupt vessel-tracking systems in the region. The practice of ships disabling AIS in high-risk waters is also reducing the timeliness and reliability of tracking information.