American access to the Panama Canal, one of several new directives outlined in what amounts to a major overhaul of US strategic priorities, according to a new memo that was sent to senior leaders and reviewed by CNN.

Potential plans range from partnering more closely with Panamanian security forces to a less likely option of U.S. troops' seizing the canal by force, U.S. officials told NBC News.

Donald Trump has said repeatedly that he wants to “take back” the Panama Canal but has not offered specifics about how he would do so. Here is an explanation of the history and laws governing the critical waterway.