Complex sentence: Before he joined the United States Marine Corps, Pottinger worked as a journalist for Reuters between 1998 until 2001 then he moved to "The Wall Street Journal" until his retirement from journalism in 2005.
Split into simpler sentences: Before he joined the United States Marine Corps, Pottinger worked as a journalist for Reuters between 1998 and 2001. Then he moved to "The Wall Street Journal" until his retirement from journalism in 2005.