In 1989, the Berlin Wall came down and for many the Cold War was over. In 1990, the Iraqi invasion of Kuwait introduced a new type of regional conflict. One year later, a failed coup in Moscow eventually led to the demise of the Soviet Union. Between 1989 and 1993, the world changed a lot. The threat was different and it was spreading. The players were different. The rationale for conflict was different.

To address these and other issues, in March 1993 Secretary of Defense Les Aspin called for a comprehensive Bottom-Up Review, or BUR, of the nation's strategies and plans, the composition of the defense forces and their equipment capabilities. The goal was to "rebuild from the bottom up" and more accurately define the National Security Plan for the fiscal years 1995 through 1999.

What was the right strategy for the post-Cold War world? What force structure would be needed? Which modernization programs would address these needs given the reduced defense budgets planned by the new administration? What did the industrial base and infrastructure need to look like?

On Sept. 1, 1993, Aspin announced the results of the BUR. At the center of the BUR was a defense strategy that focused upon the ability to fight and win two major regional conflicts, which might occur simultaneously, and other types of regional conflicts. Of particular concern was the threat posed by the proliferation of short-range and cruise missiles equipped to carry nuclear, biological and chemical warheads. Given these assessments, what then were the implications for ballistic missile defense?

During the Cold War, with the Soviet Union and China as the primary adversaries, national missile defense was at the foreground. The primary focus was how to protect the nation against the threat posed by long-range nuclear missiles. With the shift to regional- or theater-based scenarios, shorter range missiles were needed to provide a Theater Missile Defense or defenses against shorter range theater and tactical missiles that could be used against forward-deployed forces or American allies.

Two deployment scenarios were reviewed for national missile defense. The first, which would comply with the Anti-Ballistic Missile Treaty, saw 100 ground-based interceptors deployed at the former Safeguard ABM site near Grand Forks, North Dakota. The second incorporated space-based sensors and multiple deployment sites across the country. This proposal would require a renegotiation of the ABM Treaty with the Russia.

The BUR team evaluated four options for the future of national missile defense. The first would pursue a standard acquisition and would result in an initial operational capability by 2004. The second option, known as the systems Technology Demonstration Approach "would permit a prototype deployment by 2003," if a decision was made in 1999. The third and fourth options reduced national missile defense to technology programs with or without a Brilliant Eyes space-based asset.

Meanwhile, the allotted funding would "preserve an adequate industrial base in critical technology areas." Under this proposal, a deployment could be achieved 10-15 years from the decision point.

To address the growing threat to the theater by short-range and cruise missiles, the BUR assessed again four options, all of which incorporated a "core" set of TMD systems. The core of the TMD approach created a three-tiered defense incorporating the enhanced version of the current Patriot or the Patriot Advanced Capability, Level 3; the sea-based Aegis/Standard Missile Block IVA; and the Theater High Altitude Area Defense, as it was known then.

Option one began with the core TMD systems and added a sea-based upper Tier and the Corps SAM systems. The second option involved the core systems and the Navy Upper Tier. Option three was similar to the second, except that the sea-based upper tier was classified as a technology demonstration. The final option focused strictly on the four core systems with no additional programs until at least 1998.

The various options under consideration ranged in cost from $15 billion to $25 billion, much less than that $39 billion planned by the Bush administration over the same period. The recommendations of the BUR team "given the nature of the present and projected threat from ballistic and cruise missiles armed with weapons of mass destruction … [emphasized] protection of forward deployed U.S. forces in the near team."

They opted to pursue TMD Option 2 - the core systems with the addition of sea-based upper-tier to create a more robust TMD program. For the national missile defense program, the BUR recommended a technology readiness approach with a goal of preserving the necessary industrial base while continuing to develop the necessary technologies.

The end product sought to "field effective TMD systems in the shortest time possible while also 'providing a basis for a speedy decision to deploy national missile defense should a serious threat suddenly materialize.'"

Thus the BUR validated Aspin's May 1993 decision to reprioritize the missile defense programs, a decision which had accompanied his announcement of the end of the Cold War.

The impact was immediate. With a budget reduced to $18 billion over the Future Years Defense Program (FY1994-1999), primary emphasis was given to TMD Systems. The TMD programs would receive $12 billion in the new budget layout. Over the same period, the national missile defense funding meanwhile was scaled back dramatically to "approximately $600 million per year as a hedge against the emergence of a greater long-range missile threat than is now projected."

At the same time research and development was cut to $3 billion split between follow-on technology and research and support.