The operation is being conducted through the Houthis' Humanitarian Operations Coordination Center, emailing them travel details and assurances that their vessels and crews have no links to the US, UK or Israel. The group usually responds within 24 hours, with approvals reportedly valid for seven days.
In one case, the Chinese container ship Zhong Cheng Chang Ling was cleared in September and instructed to keep its tracking transmitter and marine radio channel active throughout the passage.