Kim Yo Jong, the powerful sister of leader Kim Jong Un, warned in a statement that Pyongyang would see it as a "declaration of war" if the US took military action against the North's strategic weapon tests. In a separate statement, the chief of the Foreign News Section at North Korea's Foreign Ministry accused the US of "aggravating" the situation by conducting a joint air drill with a B-52 bomber on Monday and planning US-South Korea field exercises. Around 28 500 US troops are stationed in South Korea as a legacy of the 1950 to 1953 Korean War, which ended in an armistice, rather than a peace treaty, leaving the countries technically at war