United and US Airways were in advanced merger talks in late April 2008, following the announcement that Continental had broken off talks with United. In June 2008, CEOs of both United Airlines and Continental Airlines signed an alliance pact that led to their eventual merger. The alliance was an agreement to link international networks and share technology and passenger perks. This agreement was termed a "virtual merger" as it included many of the benefits of a merger without the actual costs and restructuring involved. The alliance took effect about a year after Delta Air Lines and Northwest Airlines completed their merger, as that released Continental from the SkyTeam contract and allowed for the required nine-month notice. Additionally, Continental joined the Star Alliance, as Delta and Northwest merged.