In the early 1980s Central America suffered from civil wars and interstate tensions that devastated societies and economies. Shortly after taking office in 1986, President Arias proposed a peace initiative later known as the Esquipulas Agreement. The plan called for cease-fires, democratic elections, withdrawal of foreign forces, and verification by international observers. In August 1987 the leaders of five nations signed the document, launching a regional de-escalation process. Drawing on Costa Rica’s own experience without a standing army, Arias showed that security could be built through dialogue rather than weapons. His actions eased humanitarian crises and highlighted the value of international cooperation. For these achievements he received the 1987 Nobel Peace Prize.

The Arias Plan synthesized the earlier diplomatic efforts of the Contadora Group and elevated them into a legally binding treaty. The Esquipulas II Accord signed on 7 August 1987 stipulated (1) a cease-fire within 60 days, (2) deployment of international verification missions within 90 days, (3) free and fair elections, (4) withdrawal of irregular forces and foreign troops, and (5) explicit guarantees of human rights. Costa Rica’s abolition of its military in 1948 served as a persuasive model during negotiations. Arias criticized the U.S.–Soviet proxy dynamics and redefined security through a region-driven framework. Although issues of sovereign interference were debated, Article 8 of the treaty clarified non-intervention commitments. After the accord, the UN and OAS created observer missions (CIAV-OAS, ONUCA) that supervised disarmament and election processes. Nicaragua consequently held the 1990 elections, while El Salvador reached the 1992 Chapultepec Peace Accords, establishing long-term structures for peace.

The Arias Plan remedied deficiencies in Contadora Documents 1986A/B by synchronizing cease-fire and democratization benchmarks, thereby avoiding time-inconsistency problems. Its text adopted a two-tier compliance mechanism of National Reconciliation Commissions and an International Verification Commission to combine domestic ownership with external legitimacy. Because demobilization of U.S.-backed Contra forces required congressional assent, Arias pursued a hybrid strategy that blended multilateral diplomacy with bilateral Memoranda of Understanding. He further linked OAS Charter Chapter III collective-security clauses with UN Charter Article 52 regional arrangements to safeguard the legality of intervention. Consequently, the plan is viewed as the inception point for a security community in the Central American regional IR structure and as a theoretical precursor to later inter-American human-rights architectures.