During the second week of August 2023, the Union of Indigenous Communities of the Northern Zone of the Isthmus (Ucizoni) in Oaxaca, Mexico, denounced acts of intimidation and harassment by the police and members of the Navy, whose presence in the vicinity of the organization's offices has allegedly increased since the beginning of August 2023. During the second week of the month, Ucizoni registered "the harassing and intimidating presence" of the police on at least five occasions, both at the Union's offices and at the home of its coordinator Carlos Beas. The organisation also registered the presence of individuals on motorcycles on two occasions late at night by the offices and Carlos Beas' house. On 14 August 2023, Juana Inés Ramírez, member of Ucizoni, was detained by members of the state police, whilst her vehicle was searched by the police and the Navy.

Ucizoni has been threatened and attacked on different occasions due to their work defending indigenous rights in the South of Oaxaca. Threats against them have increased since the announcement of the Inter-Oceanic Corridor of the Isthmus of Tehuantepec (CIIT) project, with the participation of majority State-owned company Ferrocarril del Istmo de Tehuantepec S.A. de C.V., in the region. This project includes the eventual development of a commercial-industrial corridor between the Gulf of Mexico and the Pacific Ocean, the construction of commercial ports, a network of primary and secondary roads, digital connectivity networks, a gas pipeline, as well as ten industrial parks. The project also plans to connect with another large-scale investment project, the "Tren Maya". These projects pose a risk to the livelihoods of the 12 indigenous communities living in the area, as well as to the preservation of their territory and environment.

In March 2023, the police attacked a UCIZONI protest camp, which had been blocking the Mogoñe Viejo-Vixidu railway line for 24 days. Following the attack, 11 community members received notifications that they were being criminally investigated, and on 28 April, 6 of those community members, Maria Magdalena Martinez Isabel, Esperanza Martinez Isabel, Elizabeth Martinez Isabel, Eliodoro Martinez Isabel, Fernando Hernández Gomez y Adela Severo Teodoro, were arrested. In the same month, Carlos Beas, director of the organisation, received death threats.