Freedom of navigation is a customary right codified into the 1982 United Nations Convention on the Law of the Sea (1982 unclos) which covers both innocent passage in the territorial seas and free passage in the Exclusive Economic Zones of coastal States and high seas. Under the 1982 unclos, freedom of navigation is a non-discriminatory right applied to all types of vessels regardless of their nationalities. As a member of the 1982 unclos since 1994, Vietnam has incorporated into its national legislations provisions on freedom of navigation, along with other regulations on safety of navigation, sea-lane designation and marine environment protection. The incorporation process witnessed two separate periods of development. From 1980 to 2012, under Vietnam’s laws, there was no explicit provision on free passage, and the innocent passage of war ships shall be subject to prior notification to and authorisation of Vietnam due to national security concerns. After 2012, free passage was expressly recognised in the Exclusive Economic Zone of Vietnam and high sea. The requirement for prior authorisation for innocent passages of war ships was also removed for better fulfillment of Vietnam’s treaty obligations under the 1982 unclos. The prior notification requirement, nevertheless, remained with the purpose to facilitate safety of navigation. Failing to make prior notification would not be a bar to warship conducting innocent passage in the territorial sea of Vietnam.