The prime ministers of Sweden and Finland said at a press conference Wednesday they’re strongly considering joining NATO in response to Russia’s invasion of Ukraine—a move that would ensure alliance members would come to their defense should Russia invade, but that Moscow has warned would lead to retaliation.
NATO, or the North Atlantic Treaty Organization, is a 30-country alliance that’s most notably joined together by a “collective defense” agreement that means “an attack against one ally is considered as an attack against all allies” requiring other countries to aid the attacked country militarily.