The president previously supported Britain's agreement to hand back sovereignty of the Indian Ocean archipelago, where the U.K. continues to lease the U.S.-U.K. Diego Garcia military base.
Crews had already removed thousands of tons of fuel oil from the ship to stave off further harm to the environment. Still, scientists say it's the worst ecological disaster in the country's history.
A Japanese-owned cargo ship ran aground in late July and began leaking oil a few days ago. Now a crack has expanded in its hull. The island nation is home to species that live nowhere else.
