If one nation oppresses or injures another, it is the duty of all other nations to unite to prevent such oppression.
'Abdu'l-Baha writes:--"It may happen that at a given time warlike and savage tribes may furiously attack the body politic with the intention of carrying on a wholesale slaughter of its members; under such a circumstance defense is necessary." Hitherto the usual practice of mankind has been that if one nation attacked another, the rest of the nations of the world remained neutral, and accepted no responsibility in the matter unless their own interests were directly affected or threatened.

The whole burden of defense was left to the nation attacked, however weak and helpless it might be.

The teaching of Baha'u'llah reverses this position and throws the responsibility of defense not specially on the nation attacked, but on all the others, individually and collectively.

As the whole of mankind is one community, an attack on any one nation is an attack on the community, and ought to be dealt with by the community.

Were this doctrine generally recognized and acted on, any nation contemplating an aggression on another would know in advance that it would have to reckon with the opposition not of that other nation only, but of the whole of the rest of the world.