Answer: "Not to provide the British or Dutch with guarantees" means that a country or government has decided not to offer formal assurances of support or protection to the British or Dutch, particularly in the context of international relations or conflicts. This could mean that a country has declined to sign a treaty or agreement that would offer such guarantees, or that they have stated publicly that they will not become involved in defending or assisting the British or Dutch in the event of a conflict. The phrase can also imply a lack of commitment or willingness to help, and suggests that the country may be pursuing its own interests or trying to remain neutral or non-aligned.
Explanation: In this passage, "not to provide the British or Dutch with guarantees" means that the United States was not willing to offer formal assurances of support or protection to the British or Dutch in the context of developing defense plans for the southwest Pacific. This suggests that the United States was not committing to a formal alliance or treaty with these countries to defend their interests in the region. This lack of commitment could mean that the United States was pursuing its own interests or trying to remain neutral, or that it did not want to get involved in any potential conflicts that might arise in the region. The passage also implies that the British and Dutch were seeking such guarantees from the United States, but were not able to obtain them.