Jang had often served as the bridge between North Korea and its Chinese ally, often visiting the latter country which the current leader of North Korea has yet to do. This made him often advocate for the positions China wanted for North Korea such as reforming the highly centralized economy, much as the former country did in the last generation. Thus to a certain extent the blatant ouster of Jang, to the point that his arrest was carried in the middle of a meeting and photographed for all the world to see indicates Kim Jong-Un intends to continue his assertion of independence from China. This desire has already been displayed this year through the North's nuclear tests, which the Chinese opposed and which led them to respond by supporting UN Security Council sanctions.
When Kim Jong-Un first came to power almost two years ago, there was some hope that he would be a reformist who would begin to open up the "hermit country" to the wider world. Yet this was not to be: North Korea instead has stepped up its bellicose rhetoric by constantly threatening to renew the war against the South which ceased some sixty years ago. The increasing fraying of relations with China threatens to further increase the isolation and block off what was hitherto a moderating influence.
Thus the arrest of Jang has served to but add tension to the region of East Asia already fraught by territorial disputes between China and Japan over the Senkakus. The United States must navigate this new situation carefully, promoting what good it can by continuing efforts to denuclearize North Korea but also be prepared to meet any sudden action by the North with strength. We cannot but hope that the removal of Jang does not signify anything worse.