The following is the Oct. 26, 2017 Congressional Research Service report, A Shift in the International Security Environment: Potential Implications for Defense.
From the report
World events in recent years have led observers, starting in late 2013, to conclude that the international security environment has undergone a shift from the familiar post-Cold War era of the past 20 to 25 years, also sometimes known as the unipolar moment (with the United States as the unipolar power), to a new and different situation that features, among other things, renewed great power competition with China and Russia and challenges by these two countries and others to elements of the U.S.-led international order that has operated since World War II.
A previous change in the international security environment—the shift in the late 1980s and early 1990s from the Cold War to the post-Cold War era—prompted a broad reassessment by the Department of Defense (DOD) and Congress of defense funding levels, strategy, and missions that led to numerous changes in DOD plans and programs. Many of these changes were articulated in the 1993 Bottom-Up Review (BUR), a reassessment of U.S. defense plans and programs whose very name conveyed the fundamental nature of the reexamination that had occurred.
The recent shift in the international security environment that observers have identified—from the post-Cold War era to a new situation—has become a factor in the debate over the size of the U.S. defense budget in coming years, and over whether the Budget Control Act (BCA) of 2011 (S. 365/P.L. 112-25 of August 2, 2011) as amended should be further amended or repealed. Additional emerging implications of the shift include a new or renewed emphasis on the following in discussions of U.S. defense strategy, plans, and programs:
- grand strategy and geopolitics as part of the context for discussing U.S. defense budgets, plans, and programs;
- U.S. and NATO military capabilities in Europe;
- capabilities for countering so-called hybrid warfare and gray-zone tacticsemployed by countries such as Russia and China;
- capabilities for conducting so-called high-end warfare (i.e., large-scale, high- intensity, technologically sophisticated warfare) against countries such as China and Russia;
- maintaining U.S. technological superiority in conventional weapons;
- nuclear weapons and nuclear deterrence;
- speed of weapon system development and deployment as a measure of merit in defense acquisition policy; and
- minimizing reliance in U.S. military systems on components and materials from Russia and China.
The issue for Congress is whether to conduct a broad reassessment of U.S. defense analogous to the 1993 BUR, and more generally, how U.S. defense funding levels, strategy, plans, and programs should respond to changes in the international security environment. Congress’s decisions on these issues could have significant implications for U.S. defense capabilities and funding requirements.