President Trump has decided that the United States is engaged in a formal "armed conflict" with drug cartels his team has labeled terrorist organizations and that suspected smugglers for such groups are "unlawful combatants," the administration said in a confidential notice to Congress this week. The notice was sent to several congressional committees and obtained by The New York Times. It adds new detail to the administration's thinly articulated legal rationale for why three U.S. military strikes the president ordered on boats in the Caribbean Sea last month, killing all 17 people aboard them, should be seen as lawful rather than murder.