China's navy is reported to have issued eight warning messages to a U.S. military spy plane. The plane flew over several man-made islands that China is using to secure its territorial claims in the disputed South China Sea.
An official from China's foreign ministry said he was not aware of the event, but said he hopes the "relevant country" can respect China's "indisputable sovereignty" over the area.
U.S. officials have expressed concern about China's land-reclamation efforts at seven sites in the Spratly Islands, parts of which are also claimed by the Philippines, Vietnam, Malaysia, Brunei and Taiwan.
