WASHINGTON (AP) — Vowing to protect fragile marine life, President Barack Obama acted Tuesday to create the world’s largest ocean preserve by expanding a national monument his predecessor established in waters thousands of miles from the American mainland.

The designation for a remote stretch of the Pacific Ocean marks a major symbolic victory for environmentalists, who have urged the president to take action on his own to protect the planet as Congress turns its focus elsewhere. But the initiative will have limited practical implications because little fishing or drilling are taking place even without the new protections.