At first glance, it appeared that the US had military treaty obligations to both parties in the war, bound to the UK as a member of NATO and to Argentina by the Inter-American Treaty of Reciprocal Assistance (the "Rio Pact"). However, the North Atlantic Treaty only obliges the signatories to give support if the attack occurs in Europe or North America north of the Tropic of Cancer, and the Rio Pact only obliges the US to intervene if one of the adherents to the treaty is attacked—the UK never attacked Argentina.