Pop-punk quartet Sum 41 has cancelled their remaining dates on the Vans Warped Tour after frontman Deryck Whibley was attacked last Thursday (Aug. 5) during the band’s visit to Japan. The unprovoked incident aggravated the singer’s previous slipped disk injury and forced the group to scrap five Warped Tour performances, including the tour’s stop in Boise, ID tonight (Aug. 13). After traveling across North America with the Warped Tour earlier this summer, Sum 41 was preparing to perform at Japan’s Summer Sonic festival when the attack occurred. Although the band played the scheduled shows in Osaka and Tokyo last weekend (Aug. 7-8), Whibley’s injury did not improve and the group decided to take a touring break. “We were very excited to be back in front of our fans and are very disappointed that we have to pull off the tour,” said drummer Steve Jocz. “We know that it would be more frustrating for the fans if we can’t give it our all. Deryck is doing everything he can to get himself better and we’re there for him.” Whibley is expected to make a full recovery, and the band plans to kick off a European trek on Aug. 31 in Lausanne, Switzerland.