The project was regarded as a contractual obligation by the Beatles, who were asked to supply four new songs for the film. Some songs were written and recorded specifically for the soundtrack, while others were unreleased tracks from other projects. The album was issued two months after the White Album and was therefore not viewed by the band as a significant release. Yellow Submarine has since been afforded a mixed reception from music critics, some of whom consider that it falls short of the high standard generally associated with the Beatles' work. It reached the top 5 in the UK and the US, and has been reissued on compact disc several times.