Sweden and Finland are not members of NATO, though both nations have some nominal ties to the alliance for the sake of coordination. Still, they’re not proper members, so NATO’s Article V collective defense requirement doesn’t apply.
NATO’s Commodore Hans Helseth, however, argues that NATO should feel a “moral obligation” to defend Sweden and Finland militarily if either one of them gets attacked, adding the nations are welcome to join the alliance.
Sweden and Finland have long valued their positions of neutrality, which affords them certain advantages during periods of NATO-Russia tensions. It also means they aren’t obliged by treaty to jump into any huge wars NATO gets sucked into .
While there are some in each nation arguing in favor of joining NATO, it appears there is little reason for them to consider doing so, particularly if it turns out NATO feels obligated to come to their defense militarily at any rate.