Kenya said on Thursday it had told the United Nations it will shut by June 2022 two camps holding over 410,000 refugees who fled from wars in the east and Horn of Africa, adding it planned to repatriate some and give others residency.

The interior ministry made the announcement on Twitter about five weeks after ordering the closure of the Dadaab and Kakuma refugee camps and giving the United Nations two weeks to present a plan to carry this out.

The U.N. refugee agency (UNHCR) replied by asking the government to ensure that vulnerable refugees would still be protected under its timeline for the closure. A Nairobi spokesman for the UNHCR did not immediately respond to a request for comment on the latest announcement.

One of the two refugee camps in Northern Kenya, Dadaab, close to the sensitive border with war-racked Somalia, was set up in 1991. In 2011, amid famine and chaos in Somalia, it was the world’s largest camp.

Thursday’s announcement appeared to be the decisive step by Kenya after years of discussion about closing Dadaab. The Interior Ministry tweet included a photo of a meeting between Minister Fred Matiang’i and UNHCR Chief Filippo Grandi.

“Among the precursory activities in (the government’s) roadmap is repatriation of refugees to countries of origin and socio-economic integration of some of them through Work/Residence Permits (in Kenya),” the tweet read.

Legal challenges could follow. Earlier this month, a Kenyan court ruled against the closure of the camps.

Authorities in Nairobi first announced their intention to shut the Dadaab camp back in 2016, citing national security concerns over infiltration by militants from the Somalia-based Islamist group al Shabaab.

Relations between Kenya and Somalia have deteriorated badly in the past year since Mogadishu cut diplomatic ties with Nairobi, accusing it of interfering in its internal affairs.

Kenya contributes troops to the African Union peacekeeping force deployed in Somalia to curb the al Qaeda-linked al Shabaab that seeks to topple the government. In a sign of the tense relationship, Somalia said in January it had lost confidence in Kenyan troops serving in the peacekeeping mission.