The Gulf Cooperation Council (GCC) on Oct. 16 held its first high-level summit with the European Union in Brussels. In the weeks prior, the six-member bloc engaged in joint ministerial meetings with Brazil, India, and Russia, while also initiating informal dialogue with Iran. These developments come at a time when the GCC, just a few years ago, was seen as teetering on the brink of irrelevance—especially amid the 2017-21 blockade of Qatar by the Arab Quartet (Bahrain, Egypt, Saudi Arabia, and the...