Bolivia has deployed an unusual weapon in a maritime dispute with Chile - a colossal flag stretching about 200 km (124 miles).
Bolivia wants to recover access to the Pacific Ocean, which it lost to Chile in a 19th Century war.
It is due to take its demand to the International Court of Justice later this month.
Chile says there is nothing to negotiate and its sovereign borders are fixed through a treaty after the war.
Background to the dispute:
- After its defeat by Chile in the War of the Pacific, Bolivia lost 120,000 sq km of land and 400km (250 miles) of coastline, becoming a landlocked country
- Bolivia says that Chile has an obligation to "negotiate a sovereign access to the sea for Bolivia"
- It brought the territorial dispute in 2013 to the International Court of Justice in The Hague
- Chile and Bolivia have not had full diplomatic relations for several decades
Source: BBC Monitoring
The Bolivian government said the flag is the world's biggest, and extended between the cities of La Paz and Oruro.
The banner is made of blue cloth decorated with Bolivian national symbols and is about three metres wide.
The current borders were agreed after the 1879-1884 War of the Pacific. The war, which pitted Chile against Bolivia and Peru followed attempts by Bolivia to tax a Chilean nitrate company in violation of a previous treaty. Chile despatched troops to the north in protest and within weeks the two sides were at war.
Bolivian President Evo Morales said in October 2017 that Chile made a secret offer in 1975 to grant his country access to the Pacific Ocean through a 10km corridor.
Speaking at the flag's unfurling he called it a "flag of maritime vindication".
The Guinness World Records organisation said they had no plans to certify whether the flag was indeed the world's biggest.
Correction 18 April 2018: This article has been amended to explain in more detail the causes of the War of the Pacific.