NATO Secretary-General Jens Stoltenberg said Ukraine's accession to the Western military alliance will not happen while the war is going on but that the membership path is there for the future. Stoltenberg told an event organized by the U.S. German Marshall Fund in Brussels that "we all agree Ukraine will become a member of the alliance." But, he added, "to become a member in the midst of a war is not on the agenda." Stoltenberg said Russian President Vladimir Putin has made "two big strategic mistakes" -- underestimating the "bravery" and "resolve" of the Ukrainians and underestimating NATO allies and partners.