As of recent, there has been a lot of debate on if President Trump needs to tell the American public about dealings with leaders and the escalating North Korean issue. The simple answer is: No. The President of the United States does not have to tell anyone about U.S. dealings as Head of State, decisions as Commander-In-Chief, or even reasons for a pardon. The three co-equal branches of government are separate, but equal on purpose to prevent power grabs.
The President of the United States of America has many privileges and powers both enumerated and implied. One of the implied powers of the United States is the concept of executive privilege. Famously established in 1974 with the Supreme Court case U.S. v Nixon, executive privilege gives the right to executive branch employees to resist giving information to either the judicial or legislative branch in reference to executive branch matters.
However, I would argue the President has a moral and leadership obligation to the American people to calm their nerves. Members of Guam and the West Coast are getting very nervous about the potential of a Nuclear Strike against the United States and its territories. The President has every right to keep negotiations, threats, and methods of dealing with North Korea secret. The President himself he is not going to show his hand. However, the information asymmetry does cause many citizens of the United States to be worried about their safety and I believe, that while it is not required, the President should do more to make the tax paying, patriotic, and America loving citizens feel safer. There is no easy solution to this issue, we all understand; we just want to be sure that the government is going to TRY to keep us safe.