As the U.S. and China continue hashing out trade negotiations, a new player has joined the fray: President Donald Trump's national security advisor, John Bolton.

A National Security Council official told CNBC that it was only "natural" that Bolton be involved in recalibrating the U.S. trade relationship with China.

"Rebalancing trade and investment relations are an important component of the President's overall strategic approach to China, and therefore it is natural that the National Security Adviser would play a role in ensuring U.S. economic officials' ongoing discussions with China are framed within that strategic approach," the official said.

Bolton's involvement in trade negotiations signals a broadening scope of authority for the president's top national security aide, whose views on the U.S.' shifting relationships with North Korea and Iran were central points of scrutiny when he was appointed in March.

The high-stakes trade talks between the U.S. and China come as the Trump administration prepares for a June summit with North Korean leader Kim Jong Un, a frequent target of Bolton's criticism over the years. North Korea, likewise, recently criticized Bolton while threatening to pull out of the landmark meeting. China, which is North Korea's biggest and most important ally, has played a key role in arranging diplomatic connections between the communist dictatorship and the U.S.

The hawkish Bolton has also been outspoken on China trade policy. In a talk-radio interview in March, Bolton said China has for too long "taken advantage of its place in the world" through "the trade arrangements it has with the United States and other countries," multiple outlets reported.