Philippine navy blocked by China at disputed Second Thomas Shoal.Philippine navy blocked by China at disputed Second Thomas Shoal.
Chinese ships fire water cannons, forcing Philippine retreat from coral reef.
Philippine military condemns "excessive" action, cites violation of international law.
Second Thomas Shoal, Spratly Islands: contested territory with fish, gas, strategic value.
China defies 2016 tribunal ruling favoring Philippines; tensions escalate in region.
Philippines urges adherence to negotiations for South China Sea stability.