Three Chinese Navy ships tied up in San Diego Tuesday for a four-day visit. That was reported by kpbs.org.

The frigates Yancheng and Daqing, and the oiler Tai Hu arrived at the B Street Pier . This is the third visit by Chinese Navy ships to San Diego in the last three years.

Crew members were being hosted by sailors from the San Diego-based cruiser USS Cape St. George. They’re scheduled to take part in sporting events and cultural exchanges designed to build trust and foster cooperative relationships, according to the Navy.

The visit comes amid some tension between the United States and China over a telephone call that President-elect Donald Trump recently accepted from the president of Taiwan in violation of the protocol stemming from what has been Washington’s One China policy since 1979. The Chinese submitted a diplomatic protest Saturday.