The band broke the news Sunday evening on their Facebook page, posting a message that read:
"Billie Joe is seeking treatment for substance abuse. We would like everyone to know that our set was not cut short by Clear Channel and to apologize to those we offended at the iHeartRadio Festival in Las Vegas. We regretfully must postpone some of our upcoming promotional appearances."
At press time, it's not clear just what appearances will be scrapped in support of the band's ¡Uno! album (out Tuesday), or if Armstrong's treatment will effect Green Day's just-announced tour, which is set to kick off in November. A rep for the band could not be reached for comment by MTV News.
Armstrong launched into a rant during Green Day's Friday-night performance at iHeartRadio after being told that the band needed to wrap up their set, shouting "I'm not f---ing Justin Bieber, you motherf-----s. You've got to be f---ing joking ... I got one minute left." Green Day then smashed their instruments before departing the stage.
And earlier this month, Green Day were also forced to cancel a concert in Italy after Armstrong was hospitalized. His bandmates would subsequently tell MTV News that he had "severe dehydration," though he recovered in time to perform at the 2012 MTV Video Music Awards.
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