The US Navy plans to conduct another passage near disputed islands in the South China Sea in early April, a source familiar with the plan said on Friday, the third in series of challenges that have drawn sharps rebukes from China.

The exact timing of the exercise and which ship would travel inside a 12-nautical mile limit around a disputed island was not immediately clear.

The United States has conducted what it calls ‘freedom of navigation’ exercises in recent months, sailing near disputed islands to underscore its right to navigate the seas. US Navy officials have said they plan to conduct more and increasingly complex exercises in the future.

The USS Stennis carrier strike group is currently operating in the South China Sea. The next freedom of navigation exercise is unlikely to be conducted by a carrier like the Stennis, but rather by a smaller ship, the source said.

Experts predict the next US challenge to the various claims in the South China Sea could occur near Mischief Reef, a feature claimed by the Philippines and which was submerged at high tide before China began a dredging project to turn it into an island in 2014.

Mischief Reef is now the site of one of three military-length airfields China has built on man-made islands in the Spratly Islands archipelago.

US Navy ships regularly patrol the South China Sea, through which more than $ 5 trillion of world trade travels every year. China claims most of the area, and Vietnam, Malaysia, Brunei, the Philippines and Taiwan have rival claims.

In recent months, with tensions rising around China’s reclamation activities, US ships have been frequently and routinely shadowed by Chinese ships and regular communications with Chinese vessels have often been tense.

News of the planned exercise comes a day after US President Barack Obama met with Chinese President Xi Jinping at a nuclear summit in Washington.

During the meetings, Xi told Obama that China would not accept any behaviour in the disguise of freedom of navigation that violates its sovereignty, in a clear warning to the United States.

Chinese Foreign Ministry spokesman Hong Lei told Reuters on Saturday that China opposed any such exercise.

‘China consistently respects and supports the freedom of navigation and fly over that all countries’ enjoy in the South China Sea under international law, but resolutely opposes any country using so-called ‘freedom of navigation’ as an excuse to damage China’s sovereignty, security and maritime rights,’ Hong said.