South china sea has been bone of contention between USA and China lately. China claimed spartly islands and warned USA not to enter into its territorial jurisdiction - which is 12 nautical miles. USA was very cautious in its approach, but it was always on the cards that sooner or later it will show its muscle, which it eventually did yesterday by sending it vessel into territorial jurisdiction of - China-claimed - spartly island.

South china sea is an important route for trade as 50 percent of the world trade passes through this route.