Montenegro’s membership in the NATO alliance was formalized on Monday, ending a two-year long process marked by tension with Russia and an attempted coup against the former Soviet satellite state.

“We are an ally that will enjoy the benefits provided by the collective system of security with major responsibility to continue together with you unwaveringly and committedly to work towards durable peace, stability, and security of Europe and the world,” Montenegrin Prime Minister Dusko Markovic said through a translator at the State Department. “This is a task that will be passed on to the next generations.”