President Joe Biden and Western allies convened in Brussels, Belgium on Thursday for the first of three summits meant to address what NATO Secretary General Jens Stoltenberg described as “the most serious security crisis in a generation.” The Western allies met at NATO headquarters in Brussels, where they posed for a group photo before heading inside for closed-door talks expected to last several hours. Speaking to reporters ahead of the meetings, Stoltenberg said the discussions would focus on the alliance’s support to Ukraine in the context of the Russian invasion, which on Thursday hit its one month mark. “We will address this crisis together and address the threat that means for Ukraine, for NATO, and for the whole international rules-based order,” Stoltenberg said. NATO leaders will also discuss the need to bolster the alliance’s deterrence and defense over the longer term, Stoltenberg added, with the first step in this regard being …