The top officers in the U.S. and Chinese navies on Tuesday lauded progress in U.S.-China naval ties and said they were encouraged by the increased use of protocols for unplanned ship encounters at sea, a U.S. Navy official said.

U.S. Chief of Naval Operations Adm. John Richardson and China's naval commander, Adm. Wu Shengli, spoke for two hours via video conference, highlighting port visits, personnel exchanges and other measures undertaken in 2015, said the official. They agreed to continue that work this year.

The talks came amid growing tensions over Beijing's continued development of man-made islands in the contested Spratly archipelago in the South China Sea, and its decision to land commercial airplanes on one of the islands.