This is the first time the two have visited a military base without the usual coterie of high-ranking officials in ill-fitting uniforms. The official [North] Korean Central News Agency mentioned no other names while reporting on the trip.

North Korean leader Kim Jong-un visited a military base on Thursday apparently accompanied only by his sister Yo-jong, who seems to be growing into his most trusted aide.

North Korea watchers believe Kim Yo-jong may have taken on the role of a proxy to Kim due to her direct blood ties to the Kim dynasty. She has already accompanied Kim on 10 official occasions this year, the same number as for the whole of last year.

One researcher at a state-run think tank here said Kim Yo-jong is now in charge of propaganda projects in the Workers Party as well as managing the business operations of the party responsible for earning foreign currency.

The researcher said Kim Jong-un seems to have reached the conclusion that the only people he can trust since the execution of his uncle Jang Song-taek, the former eminence grise, "is his own blood."

Meanwhile, a spokesman for the North's bureau in charge of the joint Kaesong Industrial Complex, said the decision to raise wages there was "a legitimate measure" and fell under the regime's "sovereignty." The spokesman added that the wage hike is "not a subject for bargaining with the South."