A Chinese coast guard ship collided with a Philippine vessel it was seeking to block in the South China Sea, the Philippines said, marking an escalation in tensions between Beijing and the U.S. ally in a volatile area.  

The Philippine boat was on its way to deliver supplies to an outpost the country maintains at Second Thomas Shoal, about 100 nautical miles off its coast. A small detachment of marines lives there, on a dilapidated World War-II era ship the Philippines deliberately ran aground in 1999 to assert its rights. China claims Second Thomas Shoal, as it does much of the South China Sea, and calls the presence of the long-grounded ship illegal.