A massive oil tanker that a Chinese buyer had chartered to load crude oil from the port of Yanbu in Saudi Arabia reversed course just before arriving at the Bab al-Mandab Strait. The “New Champion” ship, flying the Hong Kong flag, turned around in the Gulf of Aden on Friday and is now heading east at a speed close to its maximum.

The reversal came as Yemen’s Houthis have, in recent days, allowed the passage of several ships associated with China. On Thursday, two massive tankers belonging to the state-owned company Cosco left the Bab al-Mandab with a total of four million barrels of Saudi oil and, upon passing through, announced that they had Chinese crew. According to Lloyd’s List, one of these two had obtained permission to transit.

Based on a Bloomberg report and tracking data, the New Champion was empty and spent some time drifting in the Gulf of Aden before the turnaround.

The exact reason for the reversal is not clear. According to ship brokers and insurers, some insurance companies in recent days have been unwilling to provide insurance coverage for vessels bound for Saudi ports.

On Monday, Yemen’s Houthis warned shipping companies in an email not to unload cargo or load cargo in Saudi ports.