On 25 December 2000, China and Vietnam signed the Agreement on the Delimitation of the Territorial Seas, EEZs and Continental Shelves in the Tonkin Gulf. Three and a half years after signature, in June 2004, China and Vietnam both ratified a maritime boundary agreement for the Tonkin Gulf (Beibu Gulf) and the agreement entered into force. A potentially complicating factor in the negotiation process was likely to have been the status of the Sino-French Agreement of 1887. In the end, the agreement reached indicated that even if the status of the Sino-French Agreement of 1887 was part of the negotiations, both sides eventually agreed that it would not have an impact on the delimitation of maritime zones in the Gulf of Tonkin. Another crucial issue was the impact of the islands, in particular, the Vietnamese controlled Bach Long Vi Island and Con Co Island. Especially, Bach Long Vi Island was entitled to a half suite of maritime zones (3n.m. EEZ) and would impact the tracing of a line of equidistance in the Gulf of Tonkin. Minor as the point might be, Con Co Island also would have an impact for it would play a fixing terminal point for the boundary. Article 7 of the agreement is about minerals and hydrocarbons of cross-boundary deposit, and if any single geophysical structure of oil and gas or other mineral deposits should straddle the demarcation line, an agreement is to be reached on the development of the structure or deposit and on the most effective manner to equally share the profits resulting from the development.