The Collaborative International Dictionary of English v.0.48:

Nonintervention \Non*in`ter*ven"tion\, n.
   The state or habit of not intervening or interfering; as, the
   nonintervention of one state in the affairs of another.
   [1913 Webster]

WordNet (r) 3.0 (2006):

nonintervention
    n 1: a foreign policy of staying out of other countries'
         disputes [syn: nonintervention, noninterference] [ant:
         interference, intervention]

Moby Thesaurus II by Grady Ward, 1.0:

63 Moby Thesaurus words for "nonintervention":
   autarky, avoidance, avoiding reaction, bimetallism, capitalism,
   circumvention, defense mechanism, dodge, duck,
   economic self-sufficiency, elusion, elusiveness, equivocation,
   escape, evasion, evasive action, evasiveness, forbearance,
   forestalling, forestallment, free competition, free enterprise,
   free trade, getting around, governmentalism, isolationism, jink,
   laissez-aller, laissez-faire, laissez-faireism, let-alone policy,
   let-alone principle, liberalism, line, localism, managed currency,
   neutrality, noninterference, noninvolvement, nullification,
   party line, party principle, planned economy, policy, polity,
   position, prevention, price supports, protection, protectionism,
   public policy, pump-priming, refraining, sectionalism,
   self-regulating market, shunning, shunting off, shy, sidestep,
   sidetracking, slip, the runaround, zigzag