Ground dispute How a rusting wreck became a geopolitical flashpoint

For more than two decades, a second world war-era ship, BRP Sierra Madre, has stood deliberately grounded in the remote, shallow waters of the fiercely contested South China Sea, carrying the Philippine flag and guarding against Chinese expansion.

- Rebecca Ratcliffe

But its future is increasingly precarious, and the ship has become a growing flashpoint in some of the world's most disputed waters.

The Sierra Madre, marooned on Second Thomas Shoal, in the Spratly Islands, since 1999, is effectively a shipwreck. Defence experts question how much longer it can last - and the Philippines faces a difficult decision about what to do next.

So too might the US, which has a mutual defence treaty with Manila, and considers the South China Sea, one of the world's busiest shipping routes, strategically important.