They've met before but never in North Korea itself | AFP
China's President Xi Jinping is in North Korea for a meeting with Kim Jong-un, in the first Chinese state visit to the North since 2005.
The two, who have met in China four times, are expected to discuss the stalled talks over the North's nuclear programme as well as economic issues.
China is hugely important to North Korea, as its main trading partner.
Mr Xi's visit comes a week before the G20 summit in Japan, where he is set to meet US President Donald Trump.
It will also be his first meeting with Mr Kim since the Trump-Kim meeting in Hanoi in February ended without any agreement on North Korean denuclearisation.
Why is the visit happening now?
Mr Xi's two-day visit will be the first by any Chinese leader to North Korea in 14 years and Mr Xi's first since taking power in 2012.
It is being seen as a boost for Mr Kim, who has been struggling to maintain momentum after a flurry of diplomatic activity over the past year.
The two leaders will inevitably discuss the stalled nuclear negotiations and the collapse of the Hanoi summit.
Analysts say Mr Xi will want to know what happened and whether any way can be found to move things forward, information he could then share if he meets Mr Trump in Japan.
China wants North Korea to stop missile testing | AFP/KCNA VIA KNS
Although the visit was confirmed only earlier this week, Jenny Town, managing editor of US-based analysis site 38 North, says it is not a huge surprise that it is happening now, with the 70th anniversary of the two countries establishing diplomatic ties approaching.
She says there might be some "symbolic value" in the visiting taking place just before the G20 summit, but that it's "more of a bonus than a deciding factor".