The SAFe principle of 'Apply systems thinking' is the one being applied when a Release Train Engineer treats Suppliers as partners. This principle is about understanding the larger context of the work and how all parts of the system interrelate. In SAFe, suppliers are considered to be part of the solution train and are critical to the delivery of value. The framework emphasizes that for organizations to achieve mutual benefits, close collaboration and trust are required with suppliers. This involves deeply involving them in the solution's definition and building activities, and working with them to help adopt Lean-Agile Mindsets and practices for the economic benefit of both parties1. Treating suppliers as partners is a strategic approach that aligns with systems thinking by recognizing the importance of every element in the value stream and fostering an environment of collaboration and mutual growth.