Arrival of US sub in Philippines sign of shifting balance of naval power

The arrival of one of America's most advanced submarines in the Philippines' Subic Bay this month may not have generated many headlines across the region, but the significance was certainly not lost on Chinese officials and the mainland's burgeoning class of online military watchers.

As the Hawaii - a Virginia-class "hunter killer" attack submarine - moored alongside a specialist service ship, the Emory Land, it became the third US sub to visit Subic Bay since May - just one more sign of a growing US military presence across East Asia amid China's rise.

While the activities of surface warships - US aircraft carriers involved in exercises off Vietnam, or the dispatch of civilian Chinese patrol craft to the Diaoyu Islands, for example - routinely hog the headlines, it is the rarely-sighted submarines that are doing some of the most sensitive work as regional navies, some supported by the US, gear up to cope with China's military modernisation.

The nuclear-powered Hawaii is based in Pearl Harbour and called in at Subic for what US officials described as a routine rest and recreation stop. The precise nature of its long-term work beneath the waves of East Asia remains unclear, but it is perhaps significant that Subic is the closest traditionally friendly port for the US to the PLA navy's southernmost submarine base, built into the side of a cliff on Hainan Island at the top of the disputed South China Sea.

"When we see the US reasserting a presence at Subic with submarines, I fear we are seeing Washington's 'pivot' in action," said one Chinese envoy. "The pivot is not just words, it is already happening - and in the meantime we are left with the question of just how far they will go to contain China."