MARRAKECH, Morocco (AP) — A United Nations accord, the "Global Compact on Migration," adopted Monday by 164 U.N. members, but not the United States, aims to improve the treatment of migrants worldwide.

Here, at a glance, are key points and details:

WHAT IS IT? A non-binding, voluntary agreement that aims to ensure "safe, orderly and regular migration."

WHY? Because migration is such a huge economic, social, political and health issue, affecting nearly every country. The U.N.'s International Organization for Migration estimates there are 1 billion migrants worldwide, or nearly one in every seven humans.

HOW WILL IT WORK? The pact encourages countries to work together, mentioning the word "cooperation" 62 times, and to fight discrimination against migrants.

WHO SUPPORTS IT? German Chancellor Angela Merkel was a key backer.

WHO OPPOSES IT? At least nine countries. In a detailed critique , the Trump administration said it could not "support a 'compact' or process" that could "impose" policy. It also said the agreement failed to "distinguish adequately" between legal and illegal immigrants. Many eastern European countries, and more recently Italy and Belgium, also voiced misgivings.

WHAT DOES THE U.N. SAY? Secretary-General Antonio Guterres said: "We are not establishing a new right to migrate. No. There is not a right for anyone to go anywhere at any time according to his or her whim. What we are establishing is the obligation to respect the human rights of migrants."

The U.N. says more than 80 percent of the world's migrants move between countries "in a safe and orderly fashion." And most migration is "South-South" — between countries in the southern hemisphere — not among people seeking to reach richer northern countries.