The changing nature and complexity of conflict structures underscore the importance of interpreting attackers’ and defenders’ strategic positions and incentives in modern security dilemmas. The mindsets and strategies that De Dreu and Gross (D&G) suggested were largely favored by defenders in asymmetric intergroup conflicts could also play an important role among attackers. Based on identity fusion, retaliatory thinking, and intergroup threat sensitivity, we propose that, like defenders, attackers could (1) be strongly fused with their in-group; (2) be motivated to intentionally signal aggressiveness, which may especially be reflected in intimidation; and (3) engage in hostile attributions of the out-group. In particular, we suggest that these characteristics may be especially reflective of attackers with strong tendencies toward self-sacrificial forms of prosociality and retaliatory mindsets. For these individuals, the boundaries between attack and defense may be highly malleable, with defensiveness readily motivating preemptive attacks, suggesting the need for identifying more specific, robust markers that discern their motives, strategies, and actions.

Though defender groups demonstrated stronger in-group identification (De Dreu et al. Reference De Dreu, Gross, Meder, Griffin, Prochazkova, Krikeb and Columbus2016a), identity fusion could also characterize attacker groups. Unlike depersonalization, which emphasizes the relegation of the personal self, identity fusion involves the merging of personal and social selves, engenders familial feelings of oneness with the ingroup, and motivates members to “do as much for the group as they would do for themselves” (Swann et al. Reference Swann, Jetten, Gomez, Whitehouse and Bastian2012, pp. 442). Identity fusion in attacker groups may galvanize highly committed members to undertake overtly confrontational and aggressive actions by empowering their personal, agentic selves that are channeled into approach-motivated states and physical engagements directed toward the out-groups (McGregor et al. Reference McGregor, Hayes and Prentice2015). For example, far-right adherents who attach tight kinship bonds to their groups (Baray et al. Reference Baray, Postmes and Jetten2009) directly and openly display their hostility and strength toward out-groups by staging large-scale protests that are marked by provocative racist chanting and that may culminate in physical assaults (Meadowcroft & Morrow Reference Meadowcroft and Morrow2017). Importantly, these types of intimidation tactics adopted to intentionally signal aggressive intent, formidability, and unity with other group members also suggest that aggressors may not necessarily seek to deceive or mismatch the target's level of defense (De Dreu et al. Reference De Dreu, Gross, Meder, Griffin, Prochazkova, Krikeb and Columbus2016a).

Intense feelings of fusion with the ingroup could also foster unusually strong sensitivity to detect potential threats and a large risk appetite for self-sacrificial action tendencies (Whitehouse et al. Reference Whitehouse, McQuinn, Buhrmester and Swann2014). We define the tendency to voluntarily accept extreme personal costs for the welfare of other in-group members (Barclay & Van Vugt Reference Barclay, Van Vugt, Schroeder and Graziano2015; Bélanger et al. Reference Bélanger, Caouette, Sharvit and Dugas2014) as “self-sacrificing prosociality” (Böhm Reference Böhm2016, p. 1). Members with high identity fusion and self-sacrificing prosociality may volunteer to undertake attack-oriented actions that involve significant risks for themselves like suicide bombers who sacrifice willingly to harm the out-group and may not serve to strategically defend the in-group (Mroszczyk Reference Mroszczyk2016).

Individuals with retaliatory mindsets who seek to return potential harm with harm and rejoice when the perpetrator(s) suffers (Gerber & Jackson Reference Gerber and Jackson2013) may tend to construe the ambiguous actions of others as hostile and aggress against the provocateur(s) readily (Topalli & O'Neal Reference Topalli and O'Neal2003). In an intergroup setting, self-sacrificial group members with retaliatory mindsets may engage in a pattern of hypervigilance (Becker et al. Reference Becker, Mortensen, Ackerman, Shapiro, Anderson, Sasaki, Maner, Neuberg and Kenrick2011) and elevated hostile attribution bias (Bondü & Richter Reference Bondü and Richter2016). These members may perceive the out-group as being deliberately inimical to the in-group (Cottrell & Neuberg Reference Cottrell and Neuberg2005), and thus aggressive retaliation is appropriate and justified (Lopes & Jaspal Reference Lopes and Jaspal2015; Raihani & Bell Reference Raihani and Bell2018). Described as the tendency to anticipate and ascribe hostile meaning to others’ behaviors in ambiguous situations (Epps & Kendall Reference Epps and Kendall1995), hostile attribution bias has been documented among road rage drivers (Sharkin Reference Sharkin2004), intimate partners in conflict (Clements & Schumacher Reference Clements and Schumacher2010), and political party supporters (Shaver et al. Reference Shaver, Segev, Mikulincer, Shaver and Mikulincer2011; Waytz et al. Reference Waytz, Young and Ginges2014) who may motivate aggressive postures more than defensive positions.

With their in-built vigilance to detect threat for the ingroup, highly self-sacrificing members with retaliatory thinking could be most eager to signal intent to harm an out-group, relative to purely defending the in-group, which may not guarantee the safety of the in-group from the out-group (Neuberg & Schaller Reference Neuberg and Schaller2016). They may reflexively interpret any action from the out-group as antagonistic and threatening for the in-group and, in consequence, react aggressively to cues that connote possible hostility from the out-group. These members may communicate clear and advance warnings of aggression to induce fear perceptions in the out-group about its (in)capability to withstand the attack from the ingroup (Altman Reference Altman2008) or loss of control (Hasan-Aslih et al. Reference Hasan-Aslih, Netzer, van Zomeren, Saguy, Tamir and Halperin2018). The in-group could be more fixated on deriving joy from seeing the out-group in a state of panic and confusion (Jackson et al. Reference Jackson, Choi and Gelfand2019) than deterring future attacks for the in-group as the central goal (Osgood Reference Osgood2017).

Consistent with the “mental hazard-precaution system” (D&G, sect. 4.2, last para.), group members with retaliatory mindsets and anticipations of conflict with the out-group may adopt an attacker posture that is prepared to self-sacrifice to inflict damage on the out-group rather than that of a defender who strives to primarily protect the well-being of the self and their in-group. Initially relying on behavioral inhibition that calls on “vigilant scanning” of threats (D&G, abstract), these members might be mobilized into behavioral activation, which potentiates them as attackers to preemptively aggress against the out-group instead of solely primarily enhancing the well-being of the in-group.

In sum, the qualities of defenders such as in-group identification, intentional signaling of aggression, and anticipating out-group hostility could also correspond to attackers in intergroup conflicts, particularly with strong self-sacrificial tendencies and retaliatory mindsets. The role of such factors indicates the need to identify interindividual differences reflecting different types of attackers and defenders, which may enable appropriate risk assessments and interventions to be developed.