Complex sentence: Speculation concerning the conflict occurred since the ending of the Korean War, but expanded when North Korea achieved the capability to reach the United States with its missile technology and tensions rose following various exchanges during the United States Presidency of Donald Trump.
Split into simpler sentences: Speculation concerning the conflict occurred since the ending of the Korean War, but expanded when North Korea achieved the capability to reach the United States with its missile technology. Tensions rose following various exchanges during the United States Presidency of Donald Trump.