The deal is a series of interlinked contracts worth about $25bn with eight major firms to develop vast gas fields. These firms are: ExxonMobil, Shell, BP, TotalFinaElf, Occidental, Philips, Conoco, Marathon.
After year-long negotiations Saudi Arabia has given last-ditch concessions but western firms are still dissatisfied with high taxes and the amount of access given to the prized gas reserves.
The projects - to be carried out in co-operation with state-run Saudi Aramco for up to 30 years - are also expected to involve the development of power plants, pipelines and water desalination projects.
Saudi Arabia hopes the projects will help convert the country's domestic utilities from oil to gas dependency, freeing up more of the country's crude oil output for export. In addition to the largest oil reserves in the world, Saudi Arabia boasts the world's fourth biggest gas reserves.
The discovery of the submarine has unveiled a few "inconsistencies." For example, how can one explain the fact that the sub was found where it needed to be searched for from the start?
When on a state visit to Singapore, Russian President Vladimir Putin promised to revisit the discussion of the 1956 Declaration between the USSR and Japan regarding the issue of the peace treaty with Japan
The TurkStream, which runs along the bottom of the Black Sea from Russia's Anapa to Turkey, will consist of two lines, each with a capacity of 15.75 billion cubic meters of gas a year