More than 12 years after Timothy McVeigh used ammonium nitrate fertilizer to blow up the Oklahoma City federal building, Congress quietly passed legislation this month to regulate sales of the explosive.
But the Secure Handling of Ammonium Nitrate Act of 2007, placed within an appropriations act and signed by President Bush on Wednesday, falls far short of the strict law that some in the counterterrorism community and federal law enforcement were hoping for.
"The bill really does not guarantee anything for the security of the citizens of the United States," said Bill Albright, a Defense Department consultant who spent his career at the Bureau of Alcohol, Tobacco, Firearms and Explosives.
The law, which the fertilizer industry supported, leaves the United States with weaker controls on ammonium nitrate than Britain, Germany, Australia, Israel, Saudi Arabia and many other nations. Such materials have been used in terrorist bombings around the world, including the attacks on U.S. embassies in Tanzania and Kenya in 1998.
A series of last-minute revisions to the legislation has left federal officials, outside experts and even some in Congress uncertain about exactly what it mandates.
A spokeswoman for the Department of Homeland Security said Saturday that "at this time, DHS is still reviewing the new law and considering how to harmonize it with existing chemical facility rules."
The new measure creates requirements for the licensing of ammonium nitrate facilities, registration for purchasers and a framework for establishing what kinds of ammonium nitrate will be regulated - but leaves the specifics up to bureaucrats to decide later.
Clamping down on ammonium nitrate has been a difficult security decision, taking years longer than actions to tighten controls on other explosives, nuclear materials, airport security and a range of other potential security weaknesses.
U.S. consumers account for the use of about 8 billion pounds of ammonium nitrate annually. About half of that goes to the explosives industry and agriculture uses the rest, according to industry and government figures.
What kinds of ammonium nitrate to regulate has been a major sticking point. The Bureau of Alcohol, Tobacco, Firearms and Explosives and Defense Department officials have pushed for stricter rules on any potentially explosive blends of fertilizer.
The main sponsor of the bill was Rep. Bennie Thompson, D-Miss., who chairs the House Homeland Security Committee and has jurisdiction over DHS. Mississippi is one of the nation's largest producers of ammonium nitrate, according to the Fertilizer Institute.
In October, the House passed Thompson's bill that controlled sales of ammonium nitrate fertilizer containing 33 percent or more nitrogen - and left it to the secretary of the Department of Homeland Security to set lower limits.
In last-minute revisions, however, the 33 percent threshold was removed from the bill and the decision of what to regulate was left entirely to DHS.
Tests conducted by the Defense Department since the Oklahoma City bombing have demonstrated that the fertilizer can blow up with as little as 10 percent to 25 percent nitrogen content, according to ATF and defense officials.