North Korea has sent one of its top military official as Kim Jong-un’s “special envoy” to Beijing, state media reports, at a time of cooling relations with its closest ally.

Choe Ryong-hae arrived in the Chinese capital on Wednesday accompanied by a high-powered delegation in what appeared to be an attempt to mend strained relations between the two neighbors.

Choe, vice chairman of the country’s top military body, is believed to be the highest-ranking North Korean official to visit China since late leader Kim Jong-Il in August 2011.

According to the Chinese media Xinhua News Agency, Choe met Wang Jiarui, head of the ruling Chinese Communist Party’s International Department.

The high-level visit comes amid an apparent toughening of Beijing’s stance in the wake of Pyongyang’s third nuclear test. Beijing backed expanded UN sanctions against Pyongyang, including a suspension of financial transactions with North Korea’s Foreign Trade Bank, after expressing frustration with the reclusive state.

Experts said the timing of Choe’s visit was significant ahead of a scheduled summit between US President Barack Obama and China’s new leader Xi Jinping next month.

“Choe is Kim Jong-un’s closest confidante, so Kim is sending his highest possible envoy to China ahead of the summit,” Professor Yang Moo-Jin of the University of North Korean Studies in Seoul told AFP.

“This will be Kim’s way to deliver his message to Obama concerning peace on the Korean peninsula and the nuclear issue,” he added.