Commander Nate Christensen, spokesman of the U.S. Pacific fleet, told CNN there have been 18 unsafe or unprofessional interactions with China and one with Russia since 2016.
Most incidents reportedly happened during 2017. At least three that took place in February, May, and July involved Chinese fighter jets unsafely intercepting Navy surveillance planes.
The U.S. frequently conducts freedom of navigation operations in the South China Sea to challenge China's maritime claims in the area. This has resulted in several incidents throughout the years.
The most recent encounter occurred on September 30 while the USS Decatur was sailing near Gavin Reef in the South China Sea's Spratly Islands.
PRC destroyer Luyang reportedly came within 135 feet of the American vessel's bow, forcing it to maneuver to avoid a collision.
The U.S. Air Force has had at least one encounter with China during the same period. In May 2017, Chinese SU-30 fighter jets came within 150 feet of a radiation detection plane over the East China Sea. One SU-30 was reportedly flying upside down directly above the American plane.
Incidents are typically addressed through diplomatic and military channels, but the frequency of such encounters raises the possibility of a collision or clash that could spark major conflict between Washington and Beijing.