Mexico rejects claims by Texas officials that nine islands in the Rio Grande belong to the country, insisting that no US state can unilaterally change the international border. Mexico's Ministry of Foreign Affairs states that only the International Boundary and Water Commission (IBWC), the joint US-Mexico body responsible for overseeing border and water issues, can determine which country the islands belong to under the 1970 Boundary Treaty. Mexico says it will monitor developments and address the matter through established bilateral channels.