The recent presence of United States Navy warships in the West Philippine Sea (WPS) is part of a routine freedom of navigation operation (FONOP), according to U.S. Ambassador to the Philippines MaryKay Carlson.

Speaking in response to concerns over heightened tensions near Scarborough Shoal this week, including reports of aggressive maneuvers by Chinese vessels, Carlson emphasized that the U.S. is simply upholding international maritime law.

"The U.S. warships, let me address that first. That is a freedom of navigation operation or what we call a FONOP, and the United States Navy has always made it very clear, and the United States military overall, that we will fly, sail, and operate anywhere that international law allows. That’s called a straight passage or an innocent passage,” Carlson said.

The U.S. Ambassador clarified that in this particular instance, the U.S. vessels were not passing through a strait but were instead conducting an innocent passage — a legal maritime route recognized under international law that allows all vessels, including warships, to traverse coastal waters so long as it is not prejudicial to the peace, good order, or security of the coastal state.

“In this case, it wasn't through a straight, but an innocent passage through, whether it’s through territorial seas, an exclusive economic zone, or the high seas, all vessels are entitled to an innocent passage,” Carlson added.

“That kind of innocent passage is essential, and our warships conduct it to demonstrate that commercial vessels must also enjoy that same right under international law.”

Carlson's remarks came amid renewed attention on Scarborough Shoal, a hotly contested maritime feature within the Philippines’ exclusive economic zone (EEZ), where recent encounters between Philippine and Chinese vessels have raised alarm over Beijing’s increasingly assertive actions.

She underscored the economic and strategic importance of keeping sea lanes open and protected, noting that “trillions of dollars’ worth of commerce pass through the West Philippine Sea, the South China Sea, and the Taiwan Strait.”

“Exercising those freedom of navigation operations is essential to demonstrating to the world that the United States takes very seriously our obligation to uphold and defend international law of the sea,” she said.

The U.S. Navy conducts regular FONOPs across key global maritime routes, asserting navigational rights and challenging what it considers excessive maritime claims by other states — including China's sweeping claims over much of the South China Sea.

While Beijing has repeatedly condemned such operations as provocations, Washington maintains that they are a peaceful and lawful assertion of international norms.