The paper investigates the interaction between propagation buckling and upheaval or lateral buckling in deep subsea pipelines. The upheaval and lateral buckling are two possible global buckling modes in long pipelines while the propagation buckling is a local mode that can quickly propagate and damage a long segment of a pipeline in deep water. A numerical study is conducted to simulate buckle interaction in deep subsea pipelines. The interaction produces a significant reduction in the buckle design capacity of the pipeline. This is further exasperated due to the inherent imperfection sensitivity of the problem.