A deeper look at the Oklahoma City Bombing on April 19, 1995 is provided by Andrew Gumbel and Roger G. Charles in "Oklahoma City: What the Investigation Missed and Why It Still Matters." The authors construct a detailed account of the attack on the Alfred P. Murrah Federal Building by Timothy McVeigh and others, as well as giving new details about one of the most wide-ranging federal law enforcement investigations in history.
One of the reasons that agencies are more complacent about WMD training now than immediately after 9/11 is the economics of the issue. Training costs money and pulls officers off the line. Another reason that WMD training is unpopular at many agencies is that it's not by any means a pleasant thing to do.
The fourth month of the year is generally pleasant. But as the month progresses, the dates mark the anniversaries of illicit and sinister events and the fools of April are no longer funny.