I am grateful to Robert Jervis for his insights, which allow me to briefly clarify and extend my arguments by drawing upon two central themes of my book.

First, the U.S. efforts in Vietnam and Iraq demonstrate the contradictions that are inherent within such military operations. Thus, Jervis is correct that a paradox of COIN is that its scale and intrusiveness are possibly its undoing. The large footprint required for successful stability operations can fuel popular disconnect by raising expectations, drawing insurgent attacks, and fueling resentment toward U.S. personnel who seem, through local eyes, to have brought all the world's problems with them (p. 104). But the challenge for the United States is that all options involve onerous trade-offs that can undermine U.S. policies. This is true, for instance, of the “delicate balancing” that Jervis notes is required for reconciling competing groups in a conflict. By empowering local leaders—whether through delegation or deference—the United States inevitably concedes leverage to them to pursue their own agendas and resist reforms that threaten those agendas (pp. 153–54). The United States can try to mitigate these effects by empowering opposing factions (e.g., the Awakening movement); but, given the existential threat that each poses to the others, the potential result is stalemate, or worse (pp. 171–73). Again, these are but two of the many paradoxes that the United States will encounter. Others include providing necessary political and economic support to a host government that allows it to shirk, focusing on security in a country to foster its development at the cost of development, remaking government institutions by replacing those that “work” at some level, and pressuring states to curtail their support for the adversary, which then widens the war.

Second, the Vietnam and Iraq wars demonstrate limits to U.S. military capability that weigh against success, given the finite resources that the United States, as a global power, is willing to invest in a “small conflict.” I agree with Jervis that U.S. global power comes with global interests that keep the United States committed to any conflict; and I argue that the U.S. has even tried to boost its actual and apparent resolve by linking a local to a global conflict (pp. 124–25). But the question remains whether U.S. stakes in a conflict are sufficiently high to justify additional resource expenditures, once the costs of persevering are appreciated. Indeed, a downside of assuming that stakes are global is increasing the costs of an operation to make it harder to sustain (pp. 125–27). This can occur when resources are redirected unnecessarily to the conflict, a localized conflict is transformed into a “global” conflict (as the Iraq war rallied jihadists worldwide), or military strategy is distorted by focusing excessively on “external threats” (in Vietnam, from Hanoi; in Iraq, from foreign-bred terrorists).

To be sure, the U.S. operations in Vietnam and Iraq produced successes and failures. This is apparent from evaluating these conflicts by phase and “leverage target”—here, adversary forces, local populations, various third parties, neighboring states, adversary leaders, and host governments. By assessing these conflicts across time and space, my intent was to establish common points of reference to inform the running debate between those who insist that Iraq, Afghanistan, or some other conflict, is “Vietnam all over again” and those who claim that the conflict de jure is “nothing like Vietnam.” I also hoped to determine which U.S. policies worked in Vietnam and Iraq and which did not, in search of lessons about U.S. military strengths and weaknesses. Thus, I observe that the United States did achieve considerable success in both conflicts—that “the longitudinal evidence speaks, then, to the effectiveness of U.S. policy instruments when adjusted for performance even in a harsh environment” (p. 3). Saigon eventually made a huge commitment to the war effort, took control of the fighting, and established some degree of control over much of its territory (pp. 35–36, 162); and Iraq, due in part to the U.S. troop surge and outreach to Sunni groups, little resembles the simmering caldron of the civil war period (pp. 58–75).

My ultimate conclusion, however, is pessimistic—which brings me to Jervis's most challenging question. Would a different set of policies have produced a U.S. victory in Vietnam or greater U.S. success in Iraq? For me, the Vietnam case is unproblematic: The United States would have lost its will to persevere, regardless, before the adversary conceded. Iraq is the more complicated case because the answer hinges on the response to another question—specifically, “success at achieving what?” Sure, the United States might have avoided some postwar headaches with a less draconian de-Baathification policy or a larger U.S. invasion force. But, if the U.S. goal was enduring political stability, bringing unrepentant Sunnis into the government could have caused it to implode and a larger U.S. force could have baited an insurgency.

I admit my bias toward minimalism here. But I also concede that thinking small can cause an operation to fail. In my view, a Catch-22 of intervention planning weighs toward mission failure (p. 230): The United States will learn enough to formulate goals that suit U.S. capabilities only by intervening—at which point, U.S. options will have narrowed considerably. My conviction is strengthened having read Jervis's book.