One of the two private jets provided by China for North Korea's summit with the U.S. in Singapore has arrived back in Beijing. 

According to the flight route-tracking Web site Flightradar24, the jet landed at 5:29 a.m. on Wednesday. 

The site said that initially, the private jet used by the Chinese government to carry its high-level officials reported it was flying to Pyongyang, but arrived in Beijing instead. 

It is unknown whether North Korean leader Kim Jong-un was on the jet. There is speculation that Kim's top aides are probably visiting China to explain the outcome of the summit.

The other Chinese jet, which Kim travelled on to Singapore on Sunday, arrived in Pyongyang on Wednesday, after changing its flight number during its journey.