Why one government position paper does not prove adopted policy

Does finding an extreme plan in a president's papers prove that it was the administration's real policy?

No; it may be one option in a wider set, so the other papers and actual procurement decisions must also be examined.

A dramatic government plan may be one member of a larger set rather than proof of intended policy. Governments often commission position papers that range between opposing extremes, while decisions are more likely to settle among the moderate options. An author or leaker can attract attention by presenting the most alarming paper without its companions. The sound method is to locate the rest of the set and compare the proposal with actual procurement. This is a practical source-criticism test for claims about defence and naval policy.