The Philippines expressed “serious concerns” over the presence of Chinese strategic bombers in the disputed South China Sea, a spokesman for President Rodrigo Duterte said on Monday. The Foreign Ministry in Manila has taken “appropriate diplomatic action,” Harry Roque added. China’s Air Force said bombers such as the H-6K had landed and taken off from islands and reefs in the disputed region as part of training exercises last week, Reuters reports. The moves drew angry reactions from opposition lawmakers in Manila. The United States also sent ships to the disputed areas. The Philippines could not independently verify the presence of Chinese bombers in the South China Sea, Roque said. “We take note of the reports that appeared and we express our serious concerns anew on its impact to efforts to maintain peace and stability in the region,” he said.