CIA told Kennedy in 1960 that Cuba invasion plan was 'unachievable'

This week, in response to a FOIA request from the National Security Archives project at George Washington University, the CIA released most of its top-secret internal history of the 1961 Bay of Pigs invasion. The 1200 page history was written between 1974 and 1984 by Jack Pfeiffer, who later became the agency's official historian. Four of the five volumes have now been posted on the NSA's website. A fifth volume, which critique's the Agency's own internal review of the incident is still classified. 
The released documents contain a number of interesting revelations including a friendly-fire incident during which one of the CIA transport boat shot at one of the invasion force's own planes. Most interesting for presidential historians may be the minutes of a briefing given to President-Elect Kennedy on Nov. 15, 1960, during which the CIA task force expressed skepticism about whether the mission was viable with the small invasion force that the administration insisted upon, in order to maintain plausible deniability. They wrote:

Our [CIA's] original concept is now seen to be unachievable in the face of the controls Castro has institutued. There will not be the internal unrest earlier believed possible, nor will the defenses permit the type strike first planned. Our second concept (1,500-3,000 man force to secure a beach with airstrip) is also now seen to be unachievable, except as a joing Agency/DOD action. Our Guatemala experience demonstrates we cannot staff nor otherwise timely create the base and lift needed.

Reviewing the (still-classified) minutes decades later, Pfeffer wrote:

How, if in mid-November 1960 the concept of the 1,500-3,000 man force to secure a beachhead with an airstrip was envisioned by the senior personnel ... as "unachievable" except as a joint CIA/DOD effort, did it become "achievable" in March 1961 with only 1,200 men and as an Agency operation?

Good question, and perhaps some more ammunition for Tom Ricks' contention that Kennedy was "the worst American president of the previous century."
Joshua Keating @'FP'