It doesn't obligate members to respond militarily, it obligates NATO members to consider an attack against a member as an attack against them. Retaliation and any other action needs to be discussed by NATO members and can also be vetoed.
A lot of people seem to think that if article 5 is brandished, war will result, it absolutely depends on what the council will agree upon.
While Article 5 is important, its not in a "technical legal mandate" way, and there is a lot more to the alliance than Article 5, there's integrated military command, training, defense strategy, forward deployments to threatened countries, etc.
And there is Article 4 collective regional security, which has ultimately resulted in more NATO combat operations than Article 5, which has been invoked exactly once, even though the former has even less explicit obligation than Article 5.
A lot of people seem to think that if article 5 is brandished, war will result, it absolutely depends on what the council will agree upon.