The former Japanese mandate became a UN “strategic” Trust Territory under US administration. Jensen gives “12 Apr 1947”, which looks wrong.

What happened

The UN Security Council approved the trusteeship agreement, and the United States accepted it by a joint resolution of Congress on 18 July 1947; Jensen’s 12 April date is not supported by the other sources. As a “strategic” trust, its oversight lay with the Security Council, where the US has a veto. The agreement bound the US to promote islanders’ political, economic, social and educational advancement toward self-government.

Why it matters

The trusteeship framed four decades of US rule and the path to the FSM’s free association.