The United States says it is troubled by Sri Lanka's decision to end a 2002 cease-fire agreement with Tamil Tiger rebels. State Department spokesman Sean McCormack said it would now be more difficult to settle a conflict that has killed more than 70,000 people, many of them civilians, since the Tigers began fighting for an independent state for the ethnic Tamil minority in 1983, claiming discrimination by the Sinhalese majority. "All parties to the conflict share the responsibility to protect the rights of all of Sri Lanka's people," McCormack said in a statement Thursday. Sri Lanka's government has said growing violence has rendered the agreement irrelevant. Despite the cease-fire, near-daily ambushes, assassinations and airstrikes have killed more than 5,000 people over the last two years.