Defense Secretary James Mattis denied on Friday that a U.S. Navy warship conducting a Freedom of Navigation Operation (FONOP) last week violated Chinese territorial sovereignty.

“We stay strictly in accordance with international law, so there’s no violation of anyone’s sovereignty,” Mattis told reporters aboard his plane during a flight from Miami to Washington.

The comments were the first by Mattis since the FONOP, which was conducted by the destroyer USS Chafee.

The patrol was protested by the Chinese government. Beijing has laid claim to 95 percent of the South China Sea, though portions are also claimed by other nations.

The warship, an Arleigh Burke-class guided-missile destroyer, sailed near the Paracels to challenge what U.S. officials said was “excessive maritime claims.”

The Chafee did not come within 12 miles of any of the Paracels. An earlier destroyer passage by the USS John S McCain in August came within 12 miles of the disputed Mischief Reef in the Spratlys, further south in the sea.

U.S officials confirmed Chinese media reports that a People’s Liberation Army Navy (PLAN) frigate, the Huangshan, and a pair of J-11B jet fighters along with a helicopter, shadowed the Chafee during its patrol.

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