Opinion of the Court States had demonstrated a "firm and continuing international policy" of enclosing waters between the mainland and island fringes as inland waters, sufficiently well defined to cover the waters of Mississippi Sound. Rather, the inquiry was whether the States had demonstrated that the Sound met the specific requirements for a historic inland waters claim under Article 7(6) of the Convention. In the context of that claim, the variation or imprecision in the United States' general boundary delimitation principles might have been irrelevant because the State could point to specific federal assertions that Mississippi Sound consisted of inland waters. But variation and imprecision in general boundary delimitation principles become relevant where, as here, a State relies solely on such principles for its claim that certain waters were inland waters at statehood. The United States is therefore free to argue that any 10-mile rule is not sufficiently well defined to support Alaska's claim that the waters of Stefansson Sound constitute inland waters. C Alaska argues that even if principles of collateral estoppel do not apply, the evidence before the Master established that the United States had a well-defined, "firm and continuing" 10-mile rule that would require treating certain areas along Alaska's Arctic Coast as inland waters. The Master exhaustively cataloged documents and statements reflecting the United States' views and practices on boundary delimitation, both in its international relations and in disputes with various States, between 1903 and 1971. The Master found that "the exact nature of the United States' historic practice is a matter of some intricacy," and concluded that any 10-mile rule was not sufficiently well defined to require treating the waters of Stefansson Sound as inland waters. Report 55. Alaska argues that the Master afforded "undue significance to minor variations in the way the United States expressed its otherwise consistent policy over time, ignoring the prin Opinion of the Court ciple that minor uncertainties and even contradictions in a nation's practice are legally insignificant." Exceptions of State of Alaska 14 (Alaska Exceptions Brief). The relevant sources do not bear out Alaska's claim. Of particular importance for our analysis is the position of the United States in its foreign relations between 1930 and 1949. In March 1930, the United States formally proposed certain principles for delimiting inland waters to the League of Nations Conference for the Codification of International Law. See 3 Acts of the Conference for the Codification of International Law, Territorial Waters 195-201 (1930) (Acts of the Conference). As the Geographer of the Department of State later observed, where the mainland and offshore islands are assigned individual 3-mile belts of territorial sea, there will remain "small pockets of the high sea deeply indenting territorial waters." U. S. Exh. 85-223 (Boggs, Delimitation of the Territorial Sea, 24 Am. J. Int'l L. 541, 552 (1930)). Because such pockets would "constitute no useful portion of the high sea from the viewpoint of navigation," ibid., the United States proposed that countries "assimilate" these small enclaves of high seas to the adjacent territorial sea where a single straight line of no more than four nautical miles in length would enclose an enclave, 3 Acts of the Conference 201. At the same Conference, the United States also proposed a rule for straits. Where a strait connected "two seas having the character of high seas," the waters of the strait would be considered territorial waters of the coastal nation, as long as both entrances of the strait were less than six nautical miles wide. Id., at 200. Where a strait was "merely a channel of communication with an inland sea," rules regarding closing of bays would apply. Id., at 201. Under those rules, waters shoreward of closing lines less than 10 nautical miles in length would be treated as "inland" waters. Id., at 198. The United States' 1930 "assimilation" proposal is inconsistent with Alaska's assertion that, since the early 1900's, Opinion of the Court the United States had followed a firm and continuing 10-mile rule for fringing islands. If the United States' policy had been to draw a baseline connecting islands no more than 10 miles apart, all waters between that line and the mainland would have been treated as "inland waters." Under the 1930 formula, however, there were "small pockets of the high sea" between that line and the mainland, and those pockets would have been assimilated to territorial waters (that is, waters seaward of the coastline), not to inland waters (that is, waters enclosed by the coastline). Alaska now argues that the 1930 assimilation proposal "was at most one of the legally insignificant uncertainties or contradictions" rather than a change from a firm 10-mile rule. Alaska Exceptions Brief 25 (internal quotation marks omitted). Alaska took a different position before the Special Master, where it argued that the United States "unequivocally embraced the ‘assimilation' practice as the official United States position" between 1930 and 1949. Brief for Alaska on Island Fringes 54, 60-61; see Alaska Exh. 85-63 (Memorandum of United States in Response to Request of Special Master in United States v. California, O. T. 1949, No. 11 Orig., p. 19); Alaska Exh. 85-82 (Aide-Mémoire from the Department of State to the Government of Norway, Sept. 29, 1949, pp. 4-5). Alaska cannot explain why the United States would have pointed to the assimilation formula as its official position between 1930 and 1949 if a 10-mile rule for islands was in effect during that time. Nor does the United States' proposal on straits demonstrate a policy of connecting near-fringing islands with straight baselines of less than 10 miles. If the mainland and offshore islands form the two coasts of a strait, under the United States' proposal the strait would be treated as territorial waters (not inland waters) if it linked two areas of high The distance between the fringing islands may have some bearing on whether those islands in fact form the coast of a strait, but not on whether the waters they enclose are seas. Opinion of the Court territorial or inland waters. In other words, under the 1930 proposal, the character of the waters to which a strait leads, not the distance between the islands forming one coast of the strait, determines the character of the strait itself. Rather than treating the mainland and a line connecting fringing islands as the two coasts of a strait, Alaska appears to view a passageway between two offshore islands, leading to the waters between the islands and the mainland, as a strait. With this geographic configuration in mind, Alaska argues that the proposal to apply a 10-mile bay-closing rule to a strait serving as a "channel of communication with an inland sea" is "fully consistent" with a 10-mile rule. Alaska Exceptions Brief 25. But even under this approach, a rule that straits leading to an inland sea are themselves inland waters is not equivalent to a simple 10-mile rule. Again, under the United States' 1930 proposal, the character of the strait depends on the character of the waters to which it leads. A 10-mile bay-closing rule would apply only if the waters between the strait and the mainland were inland waters under some other principle. Under the simple 10-mile rule that Alaska advocates, the fact that the islands are less than 10 miles apart itself determines that the waters behind the islands are inland waters. In sum, although Alaska is correct that the United States' position at the League of Nations Conference did not call for strict application of the arcs-of-circles method, ibid., neither the assimilation proposal nor the proposal for straits is fully consistent with a simple rule that islands less than 10 miles apart enclose inland waters. The discussion above leads to the conclusion that, if the United States had a 10-mile rule at Alaska's statehood, that rule developed after 1949. Even if a rule developed within a decade of Alaska's statehood could be considered a "firm and continuing” one, Alaska has not shown that any such rule would encompass the islands off its Arctic Coast. For the period between 1950 and Alaska's statehood, Alaska fo Opinion of the Court cuses principally on the United States' position in a series of disputes with States over ownership of submerged lands in the vicinity of near-fringing islands, rather than on positions taken in its international relations. First, in 1950, the State Department and the Justice Department proposed a boundary between Louisiana's inland and territorial waters for use in the Louisiana Boundary Case. That boundary, known as the Chapman Line, followed certain barrier islands along Louisiana's southeast coast, enclosing Chandeleur and Breton Sounds and Calliou Bay as inland waters. According to Alaska, the Chapman Line shows the use of a simple 10mile rule. Second, in 1951, the Justice Department asked the State Department to outline the United States' approach to demarcating inland and territorial waters, for purposes of submerged lands litigation between the United States and California. A letter from the Acting Secretary of State stated that an island "was to be surrounded by its own belt of territorial waters measured in the same manner as in the case of the mainland." Alaska Exh. 85-94 (Letter from James E. Webb to J. Howard McGrath, Attorney General, Nov. 13, 1951, p. 3). The letter also drew upon the 1930 Hague proposals for straits, noting that the waters of a strait connecting high seas were never inland waters, but that bay-closing rules should apply to a strait serving as “a channel of communication to an inland sea.' Id., at 4. Third, in a submission to the Court in 1958, the United States commented that waters behind certain islands in Louisiana, Mississippi, and Alabama were inland waters. Brief for United States in Support of Motion for Judgment on Amended Complaint in United States v. Louisiana, O. T. 1958, No. 9 Orig., pp. 177, 254, 261. We agree with the Special Master that the United States did not exclusively employ a simple 10-mile rule in its disputes with the Gulf States and with California. The 1951 State Department letter in the California litigation merely echoed the United States' proposal at the Hague Conference |