Washington (AFP) - The Pentagon is planning to conduct more regular patrols in the South China Sea -- as many as two to three a month -- to assert freedom of navigation in disputed waters claimed by China, the Wall Street Journal reported.

The newspaper said the aim is to create a more consistent posture to counter China's maritime claims, rather than a more ad hoc approach favored during Barack Obama's administration.

US officials declined to say where or when the new patrols would be made, but said the plan developed by the US Pacific Command calls for two or three so-called "freedom of navigation" operations a month over the next few months.

Future patrols also could include US military aircraft as well as US Navy warships, the Journal said.

There have been three "freedom of navigation" operations since President Donald Trump took office in January -- the last one by the USS John S. McCain, a destroyer that collided with a cargo ship days later off Singapore, killing 10 sailors.

During the Obama administration, the US Navy conducted four such operations in the South China Sea, where China has asserted its claims by building artificial islands and establishing runways, ports and other facilities on them.

China claims nearly all of the sea, through which $5 trillion in annual shipping trade passes and which is believed to sit atop vast oil and gas deposits.

Its sweeping claims overlap with Vietnam, the Philippines, Malaysia and Brunei -- all ASEAN members -- as well as Taiwan.

Washington and Beijing have seen their relations grow increasingly fraught since a promising summit between Trump and China's Xi Jinping in April.