As the majority of American troops prepare to withdraw from Afghanistan at the end of the year, two events have revealed the stark reality of the mess the United States is leaving behind. First, reports indicate that a U.S. Army major general was killed and 14 others were wounded when a man dressed as an Afghan soldier opened fire at a base outside Kabul. The general is the highest-ranking military officer to be killed since the Vietnam War. The attack reveals just how vulnerable American troops - even those with the highest of rankings - remain. It is also another example of an insider attack by Afghan Security Forces, or by members of the Taliban who have penetrated its ranks.