<![CDATA[The challenges of urban carbon emissions and air pollution are growing, and the need for sustainable transport is becoming more pressing on a global scale, especially in developing countries, where implementation is often hampered by the lack of infrastructure and institutional capacity, and lack of policy coordination. The cooperation of West Java Province, Indonesia, and Chungcheongnam-do, South Korea, is relevant in this context because it is an example of subnational actors solving these problems with cross-border collaboration. In this study, secondary data analysis techniques based on a qualitative descriptive analytic approach is used, which is data obtained from official documents, institutional reports, and scientific literature. The results demonstrate that the cooperation has been moving toward tangible results in the form of policy implementation, such as the development of EV charging stations and electric bus rapid transit (e-BRT) in Bandung, and the Joint Working Group Meeting (JWGM) serves as a regular coordination forum that strengthens technical dialogue and operational alignment. The dynamics suggest subnational cooperation is not only a pathway to policy diffusion but also a way of creating capacity for policy implementation through the technical coordination of policy implementation across the subnational lines.Peningkatan emisi karbon dan polusi udara di kawasan perkotaan menuntut pengembangan transportasi berkelanjutan, namun implementasinya di wilayah berkembang sering terkendala keterbatasan infrastruktur, kapasitas kelembagaan, dan koordinasi kebijakan. Dalam konteks ini, kerja sama antara Pemerintah Provinsi Jawa Barat dan Chungcheongnam-do, Korea Selatan, menjadi relevan untuk dikaji sebagai upaya aktor subnasional dalam merespons tantangan tersebut. Penelitian ini menggunakan pendekatan kualitatif dengan metode deskriptif-analitis berbasis data sekunder dari dokumen resmi, laporan institusi, dan literatur akademik. Hasil penelitian menunjukkan bahwa kerja sama telah bergerak menuju implementasi kebijakan konkret melalui pengembangan e-BRT dan infrastruktur pengisian daya kendaraan listrik di Kota Bandung, dengan Joint Working Group Meeting (JWGM) berperan sebagai forum koordinasi teknis yang memfasilitasi pertukaran pengetahuan dan penyelarasan operasional. Temuan ini menunjukkan bahwa kerja sama subnasional tidak hanya berfungsi sebagai difusi kebijakan, tetapi juga sebagai mekanisme pembentukan kapasitas implementasi melalui koordinasi teknis lintas negara]]>
