The first large alliance began in 1989, when Northwest Airlines and KLM agreed to large-scale codesharing. In 1992, the Netherlands signed the first open skies agreement with the United States, in spite of objections from the European Union, which gave both countries unrestricted landing rights on the other's soil. Normally landing rights are granted for a fixed number of flights per week to a fixed destination. Each adjustment requires negotiations, often between governments rather than between the companies involved. In return, the United States granted antitrust immunity to the alliance between Northwest Airlines and KLM. Other alliances would struggle for years to overcome the transnational barriers and lack of antitrust immunity, and still do so.