Kenneth Waltz argued that the competitive pressures of the international system compel states to emulate the strongest states in the system for fear of being selected out through war (Theory of International Politics, 1979). But states actually vary significantly in capacity and effectiveness. Almost two-thirds are weak states that do not monopolize violence and tax less than Euro-American states do (around 20% of GDP against 30% in the latter). Even as states have, in general, gained capacity since 1950— manifesting in increased life expectancies, for example—this increase in state capacity has not been evenly distributed between and within states. Consequently, scholars have qualified the claim that the need to survive in the international system makes states emulate the strongest states. One such qualification is that, because interstate warfare has diminished since 1945, states have been able to survive without building capacity in the way European states did before 1945. If interstate war led to strong states, interstate peace leads to weak states.

Melissa Lee’s superb new book challenges both the conventional wisdom and the qualification to identify an overlooked way in which conflictual relations between two states since 1960 have served to weaken, rather than strengthen, one of the disputants. States are weakened through foreign subversion or when a rival state supports nonstate proxies that disrupt the state’s exercise of authority, mostly in peripheral regions. Foreign subversion, Lee clarifies, does not cause state weakness per se—most states are already weak—but it makes the extension of state power more costly and uneven. Subversion is most likely when two states have policy incompatibilities, and motivated proxies, like disaffected ethnic groups, exist that can be mobilized by one state against another. (However, the hypothesis that states will choose subversion when proxies are available [p. 63] is somewhat circular, if subversion is defined as the “empowerment of non-state actors as proxy groups” [p. 48].) Combining an innovative measure of state capacity, of which more later, with case studies of Russian subversion among its neighbors, Malaysian support of Filipino insurgents, and Thai support of the rump Khmer Rouge, she provides a range of evidence in support of her argument. The book makes two main contributions.

First, Lee challenges the view that the period since 1945 has been one of peace. Rather, she shows that the decline in interstate war has not eradicated the impositions of costs through violence in disputes. Norms limiting the use of force have had real effects in compelling states to pursue indirect, yet violent, strategies like supporting proxies. These strategies weaken the target state through different mechanisms: damaging infrastructure and harming government functionaries, requiring greater resources to police disputed areas, and reducing the target state’s ability to extract from the disputed region. In the Cambodian case, areas where Thai proxies operated were littered with land mines for years thereafter, making it harder to police or provide services there (pp. 163–64). Norms limiting the use of force do not just create a permissive environment for states to survive without strengthening through interstate war. Rather, these norms lead states to choose indirect aggressive strategies, namely foreign subversion, that lead to state weakening. This has been missed by most scholars (including this reviewer!), who have identified means that the international system uses to prop up weak states through foreign aid and such. International competition is not gone, but the form it takes today does not strengthen states.

To understand the second contribution requires some explication of Lee’s analysis of census data, which improves on extant measures of state capacity. Although almost all states now count their people—to render them “legible” for policy interventions—the accuracy of this data varies across and within states. This “illegibility” not only shows that the state cannot count its people; such a state will find it difficult to allocate services effectively. Further, variation in the accuracy of data between regions makes the state less effective in some regions relative to others (this subnational variation is not picked up by most extant data). By identifying more or less accurate census data collection, you can identify more or less effective states and where states are more or less effective. But how do you accurately identify inaccuracy? Lee leverages a novel measure: identifying anomalous distributions of reported ages. In essence, the measure picks up clusters of reported ages that end in 0 or 5, suggesting “guesstimation,” rather than the expected smooth distribution of age in a population. These clusters indicate some combination of sloppy enumeration and inaccurate birth records, both suggestive of lower state capacity (pp. 25–34). The measure has high external validity, correlating with other measures of state capacity such as infant mortality (pp. 184–85).

Lee’s deployment of these data expands our understanding of state weakness by disaggregating state capacity into two dimensions: institutionalization and consolidation. Institutionalization is the level of central state capacity; consolidation is its distribution across the territory. Very few states lack institutionalization and consolidation, but only a minority possess both. Most states are lacking one or the other dimension (pp. 18–21). This disaggregation is analytically helpful, because it identifies different barriers to improving state capacity: efforts at institutionalization, such as damming a river to generate electricity, may impede consolidation if it leads to a policy dispute with a downstream neighbor.

The book is less satisfying in its description and analysis of changes in state capacity over time. Weak states do more than they did in 1960, and although below Euro-American levels, these improvements are not trivial. Rates of immunizations in sub-Saharan Africa, for example, have tripled in the last 40 years. Such increases are bound to be unevenly distributed within states. Lee’s focus on variation in state capacity due to subversion can leave one thinking that states are staying weak or getting weaker, but the unevenness is equally indicative of overall increases in capacity.

Analytically, this complicates the mechanisms linking state capacity to subversion and to unrest more generally. Foreign subversion as a strategy is the effect of a combination of the international environment and state capacity. Lee predicts subversion is most likely when the international system constrains direct conflict and both aggressor states and target states are relatively weak (more powerful states have, if rarely, engaged in direct conquest; pp. 170–71).

This implies that subversion should become less likely if states gain capacity overall, mirroring how state strengthening is expected to reduce civil war. But other mechanisms, with countervailing effects, are foreseeable. Increases in state capacity may provide greater resources to engage in subversion; Iran, where life expectancy and literacy have risen for two decades, has supported proxies in Lebanon, Iraq, and Syria. Alternatively, an increase in capacity in a state may threaten peripheral groups in that state, motivating them to become another state’s proxy.

Most importantly, and most concerning, by increasing the cost of interstate war, state strengthening may make foreign subversion more appealing. To some degree, this supports Lee’s argument that a conflictual international system does not always build state capacity. But it also suggests that the problem may be state strengthening as much as state weakness.