Beijing has repeatedly refused to receive a phone call from US Defense Secretary Lloyd Austin, who requested to talk not with his Chinese counterpart, Wei Fenghe, but with a higher-ranking official, in violation of the diplomatic protocol, the South China Morning Post reported, citing military sources.

According to the sources, the US official’s request caused misunderstanding, as he sought to talk with Chinese Central Military Commission (CMC) Vice-Chairman Xu Qiliang, which offended the Chinese defense ministry.

Though both the CMC vice-chairman and the defense minister report directly to Chinese President Xi Jinping, according to the diplomatic protocol, Wei Fenghe should be the interlocutor of the Pentagon head, according to the report.

Pentagon spokesman John Kirby told reporters at a briefing on Tuesday that the Department of Defense was still in the market for a dialogue with Chinese military chiefs.

“We certainly desire to have a dialogue with our counterparts in Beijing, and we’re still working our way through exactly what that’s going to look like and how that’s going to transpire”, Kirby said.

The Pentagon spokesman refused, however, to further elaborate on the issue and comment on Chinese media reports saying that Beijing sent a “friendly signal” to Austin, but the US official never responded and later requested a meeting with another CMC leader, an act that also disregards diplomatic protocol.