What failures occurred during John F. Kennedy's presidency?

I would argue that John F. Kennedy's major failures were
in the area of foreign policy.  They included the Bay of Pigs invasion and the
escalation of US involvement in Vietnam.

The Bay of Pigs
invasion was a complete fiasco.  The US supported the invaders enough to make the
invasion happen, but not enough to give it any chance of success.  Allowing the invasion
to happen showed poor judgement and was a clear failure.

It
was also under JFK that the US got more deeply involved in Vietnam.  On his watch, the
US supported Ngo Dinh Diem even as he oppressed many of his people.  Then the US allowed
him to be overthrown and (probably without US approval) assassinated.  This led to a US
commitment to back a series of governments that had very little credibility with their
own people.

These two things constitute major failures of
the JFK presidency.