early operations "forced the Allies to consider the question of NATO's military responsibility for territory outside of its traditional defense perimeter, and it was one over which they were deeply divided". Disagreements between the United States and its European allies over when and how to use air power "made intra-alliance diplomacy more problematic" during the period. Many of these problems in the relationship were the result of concerns from European nations who had forces on the ground in UNPROFOR that might be taken hostage. The fact that the United States pushed for air strikes without placing its own forces on the ground in Bosnia greatly exacerbated this problem. Deny Flight also helped set the path for future UN-NATO relations. Throughout the operation, NATO "felt the frustration of having its wings clipped by a parallel UN authority", while United Nations officials worried about the effect that NATO air strikes would have on the perceived neutrality of the United Nations. Frustration with the "dual key" procedure of authorization for NATO action also led NATO officers to reject such an arrangement in the future. Admiral Leighton Smith, the commander of NATO's forces during Deny Flight, expressed this sentiment quite bluntly, saying "Don't ever have another dual key." These difficulties in negotiating the UN-NATO relationship during Deny Flight were a major factor in the decision to place later NATO forces in the Balkans under the sole control of the NATO chain of command. While many of these effects on UN-NATO relations were negative, Deny Flight also had positive implications. During the operation, NATO and the UN exchanged liaison officers for the first time in their respective histories, establishing a precedent for military cooperation between the two. The communication and coordination failures during Deny Flight also instilled "a desire for mutual understanding and common solutions" between the two organizations. This desire for cooperation was crucial to the establishment of IFOR, and later UN-NATO cooperation in Bosnia and elsewhere. Effect on the Bosnian War Deny Flight also played a significant role in shaping the war in Bosnia, although its exact impact is debated. While Richard Holbrooke, the American special envoy for Bosnia, recognized Operation Deliberate Force as "a historic development in post-Cold War relations" and as a crucial element in ending the war in Bosnia, the actual impact of Deny Flight on the course of the conflict was more muted. None of the air strikes in