Two months ago, the North Atlantic Treaty Organization took the momentous step at its summit meeting to invite Sweden and Finland into the alliance. Since then, 23 of NATO’s 30 members have ratified the decision, putting both countries on the cusp of admission. Although Turkey may yet delay matters over a political dispute, it will not stop enlargement altogether. Sooner rather than later, Sweden and Finland will join NATO and receive the ironclad security guarantees that rest at the heart of the alliance.