A Russian air force passenger plane stopped in North Korea late Sunday night before flying toward western Russia, possibly making an irregular landing on an unusual route toward Ukraine, according to NK News analysis.

It is the third confirmed Russian government or military flight between the two countries since North Korea started sending thousands of troops to Russia earlier this month, following numerous similarly undisclosed flights since last year.

Flight-tracking website Flightradar24 shows that a Russian air force Ilyushin Il-62M with tail number RA-86561 took off Sunday from Vladivostok and headed down the North Korean east coast at around 9