What were steps that led to US long-term involvement in overseas military commitments?

There were many steps that were involved in moving the US
towards long-term commitments to an overseas presence. These could
include:

• The creation of NATO. This committed the US to
  defending Western Europe from the Soviet Union. This led to the creation and maintenance of US
  bases in places like Germany and Turkey.


• The Korean War. This led
  the US to station troops in South Korea on a permanent basis. These troops remain there today.
  This also, one could argue, led the US to keep large military bases in places like the
  Philippines, Japan, and Guam.


• The French surrender at Dien Bien
  Phu and their subsequent withdrawal from Vietnam. This led to the US putting more and more
  military personnel into the country, culminating in the massive buildup after
  1964.