BEIJING -- North Korean leader Kim Jong Un plans to visit China as early as Tuesday to brief President Xi Jinping on his recent summit with U.S. President Donald Trump and discuss a negotiating strategy, sources familiar with the matter said.

Kim is expected to fly into the Chinese capital, and security preparations are already underway, according to the sources. This would mark his third trip to China in a span of just three months.

Kim's latest visit to his country's long-time ally and economic backer comes as North Korea and the U.S. prepare to hold high-level talks to follow up on their June 12 Singapore summit as soon as this week.

Trump said at the summit that the U.S. will provide "security guarantees" to the North Korean regime and cancel military drills with South Korea. But Kim was unable to come away from the meeting with a pledge on the easing of sanctions.

"We're going to get complete denuclearization; only then will there be relief from the sanctions," U.S. Secretary of State Mike Pompeo said on Thursday. China, on the other hand, is open to easing sanctions once North Korea makes a certain amount of progress on ending its nuclear weapons program.

By staging three summits with Xi in quick succession, Kim appears to be trying to show the U.S. that Chinese support for North Korea remains firm. Beijing, for its part, likely wants to use its influence on Pyongyang as a bargaining chip in its escalating trade dispute with the U.S.

Kim met with Xi in Beijing in March and in Dalian last month.