Vestra is a remote, mountainous and highly biodiverse island with extensive rainforest cover. Located in the Celestine Ocean, it is commonly referred to as 'New Galapagos Island' given the range of unique species of animal and plant life found on the island. Vestra was originally inhabited by sea-faring indigenous peoples, however the first Vestrans perished in the 17th century when they contracted influenza from the crew of a trading vessel from Imperia when it visited the island to obtain supplies.

Later in the 17th century, Imperia purported to cede Vestra to Celestia under the 1680 Treaty of Settlement under which Imperia 'relinquished to Celestia all title and claim of title to all of its possessions in the Celestine Ocean'. Beginning in the early 18th century, Celestia established several small research stations on Vestra where scientists have been undertaking research on Vestra's endemic species. Celestia also authorised the construction of several private whaling stations, and granted several oil concessions. Both the research and whaling stations were abandoned in the early 20th century and no exploration or drilling for oil occurred. However, fishermen from Celestia continued to fish in the waters around the island, and Celestia has maintained a lighthouse on the island to this day.

In 1969, Vestra was claimed by Republica, an archipelagic country several hundred kilometres to the west of Vestra. Republica issued a Presidential Proclamation claiming Vestra as the 'natural possession of Republica' citing 'new geological evidence showing that it is an integral physical component of Republica's ancient chain of islands.' Republica updated its archipelagic baselines to include Vestra and it dispatched coast guard vessels to conduct routine patrols around the island. In 1980 the Republica Parliament passed the 'Vestra Protection Act' which, among other things, declared Vestra a 'natural reserve, devoted to peace and science' and which prohibited any person from entering Vestra or the 'Vestran Marine Sanctuary' (which extends to a distance of 30 nautical miles around Vestra).

In early 2020 PetroMajor, an oil company, obtained an order from the Celestia Supreme Court recognising the validity of an oil concession granted to the company in 1920 to drill in an area 15 nautical miles from the coast. PetroMajor has called on the government of Celestia to protect what it says are its property rights deriving from national and international law.

You are an advisor in the Celestia Ministry of Foreign Affairs and have been asked to generate a brief for the Foreign Minister on the issues of international law raised by these facts.