Evaluating Possible U.S. Troop Withdrawals from Hostile Areas

On December 19, 2018, President Trump announced his intention to withdraw U.S. forces from Syria within 30 days, although Administration officials subsequently suggested that the process could take several months. Subsequent press articles indicated that the White House is also considering withdrawing "up to half" of U.S. forces in Afghanistan in the coming months, although at the time of writing the Trump Administration has stated it has not yet ordered any such withdrawal. More recently, the United States has been negotiating with Afghan Taliban representatives regarding the conditions upon which, if met, American forces might withdraw from Afghanistan. Opinions vary as whether these negotiations might lead to a successful settlement. Regardless, the suggestion that the United States might curtail its military operational commitment to those theaters raises a number of issues which may be of interest to Congress. In particular, from a strategic perspective, when is a withdrawal from a military operation appropriate?

Operational Context

The strategic question of when to withdraw is particularly complex due to the nature of the contemporary conflicts in which the United States is involved. Unlike World War II, for example, when all parties mutually agreed to cease hostilities in the wake of an overwhelming allied victory, identifying clear "winners" and "losers" in these military campaigns is often problematic. For one, there are often a multiplicity of parties to these conflicts—in Afghanistan alone, belligerents have included al Qaeda, the Taliban, the Haqqani Network, the Islamic State, the United States, the North Atlantic Treaty Organization, the International Security Assistance Force coalition, and the Government of the Islamic Republic of Afghanistan. Syria is comparably complex. As each party has its own objectives and priorities, winning agreement amongst all to cease hostilities is an inherently challenging endeavor.

Further, defining and measuring success in these campaigns has bedeviled military and civilian leaders alike, in large part due to the at times amorphous nature of the strategic goals of the campaigns themselves. Seizing and occupying terrain is generally a more straightforward military objective than, say, building legitimacy and local popular support for a centralized government or permanently eliminating terrorist safe havens. Without a clear understanding what success looks like, understanding whether enough has been done, or whether additional forces and resources might be required, becomes educated guesswork. Some key issues for Congress, therefore, are to what extent withdrawal plans proposed by the Trump Administration satisfy those criteria, and whether withdrawal either advances or sets back U.S. interests. Questions that can aid such an evaluation include the following:

Which Forces or Capabilities Are Being Withdrawn?

The unique requirements of each theater demands different combinations of forces, each with distinct missions. In Afghanistan, for example, U.S. forces are prosecuting both counterterrorism and security capacity building missions, under the rubrics of Operation Freedom's Sentinel (OFS) and the NATO-led Resolute Support (RS), respectively. Each mission is enabled by close air support and other aviation assets. With respect to countering the Islamic State in Syria, operations have included airstrikes, train-and-equip program-related activities, and "advise and assist" operations in support of local partner forces. To that end, when discussing troop withdrawals, does the Trump Administration have a specific element or aspect of the campaign it is planning to discontinue? How might that advance or impede other elements of the campaign? Further, given that other coalition partners are often reliant upon U.S. air support and other enabling assets, how might a U.S. withdrawal affect their ability to continue prosecuting operations?

What Are U.S. Objectives and How Might Withdrawal Advance or Hinder Them?

Military operations—at least in theory—have defined purposes and an end point. Withdrawing from the theaters now in question is perhaps the one thing that the United States and its coalition partners have complete control over. The timing and character of departure can be powerful tools in achieving U.S. and coalition objectives. For example, leveraging the withdrawal of a coalition can motivate parties to a conflict to work together to minimize the risk of a security vacuum once the multinational forces leave. Conversely, a poorly planned or timed departure might leave stated objectives unmet or risk leaving in place threats that can present longer-term strategic challenges. For example, some experts believe that the U.S. and coalition withdrawal from Iraq in 2011 contributed to the weakness of Iraqi security forces and the survival of militants who led the Islamic State's resurgence in the Levant region. While political and military conditions are rarely ideal, preferably the chosen departures are well planned, and conditions on the ground are such that the departure of the coalition is minimally disruptive to the local and international community. With regard to Syria and Afghanistan, do conditions on the ground in either theater support a U.S. withdrawal by enabling the United States and its partners to achieve their overall objectives? Or might extant plans, executed at this time, create more long-term risk to U.S. interests? What are the projected costs and duration of the status quo?

How Might Withdrawal Affect U.S. Global Strategy and Regional Alliances?

Many states around the world, such as South Korea, Japan, and the United Kingdom host U.S. forces on their territories in order to enhance their own stability and security. Many closely watch U.S. global troop movements to assess whether American commitments will hold into the future. On balance, most observers conclude that U.S. forward deployments in Europe and East Asia have been beneficial to the advancement of U.S. interests over the past 70 years, for instance by enabling the United States to react rapidly to changing geopolitical circumstances. A reduction in allied confidence in the U.S. commitments arguably could diminish U.S. global influence. How are allies and partners viewing possible drawdowns in Afghanistan and Syria? Are they viewing such moves as natural conclusions to the missions or a signal of U.S. abandonment of its own strategies? Has the U.S. government adequately communicated the contours of proposed withdrawals to allies and partners?