“That certainly includes the ability of our Navy to operate in international waters,” Mr. Earnest said. “This is a critically important principle, particularly in the South China Sea, because there are billions of dollars of commerce that flow through that region of the world every year — maybe even more than that — and ensuring the free flow of this commerce, and that freedom of navigation of those vessels is protected, is critically important to the global economy.”

American officials had said for the last month that the Navy would send a surface ship into the waters claimed by China, a vow widely viewed as a signal to the Chinese that most of the rest of the world does not recognize its claim on the island chain. Mr. Obama approved the move this month, administration officials said.

The president signaled the Navy maneuver last month at the annual meeting of the United Nations General Assembly, when he said that the United States had an “interest in upholding the basic principles of freedom of navigation and the free flow of commerce and in resolving disputes through international law, not the law of force.”

China, in what some Asia analysts interpreted as a gesture to pre-empt the American naval maneuver, sent warships into United States territorial waters in August. Five Chinese ships came within 12 miles of the coast of Alaska while Mr. Obama was visiting the state.

But American military officials said that the two maneuvers were not comparable, citing international maritime laws that allow passage such as the Chinese transit near Alaska if there is no other passageway for a ship to reach its destination.