Former President Barack Obama urged President Trump to continue policies that contributed to the post-Cold War era of American leadership in the world in a letter he left for him in the Oval Office on Jan. 20.

CNN reported the contents of Obama's letter to Trump upon handing over the presidency to the Republican on Inauguration Day. The letter was left in a drawer of the Resolute Desk in the Oval Office, continuing an ongoing tradition of presidents leaving a letter to their successor on their first day in office.

The letter became public for the first time Sunday. Trump promised to keep the note out of the hands of the media on Inauguration Day after thanking Obama for his kind words.

The letter stated:

"Congratulations on a remarkable run. Millions have placed their hopes in you, and all of us, regardless of party, should hope for expanded prosperity and security during your tenure.

This is a unique office, without a clear blueprint for success, so I don't know that any advice from me will be particularly helpful. Still, let me offer a few reflections from the past 8 years.

First, we've both been blessed, in different ways, with great good fortune. Not everyone is so lucky. It's up to us to do everything we can (to) build more ladders of success for every child and family that's willing to work hard.

Second, American leadership in this world really is indispensable. It's up to us, through action and example, to sustain the international order that's expanded steadily since the end of the Cold War, and upon which our own wealth and safety depend.

Third, we are just temporary occupants of this office. That makes us guardians of those democratic institutions and traditions -- like rule of law, separation of powers, equal protection and civil liberties -- that our forebears fought and bled for. Regardless of the push and pull of daily politics, it's up to us to leave those instruments of our democracy at least as strong as we found them.

And finally, take time, in the rush of events and responsibilities, for friends and family. They'll get you through the inevitable rough patches.

Michelle and I wish you and Melania the very best as you embark on this great adventure, and know that we stand ready to help in any ways which we can.

Good luck and Godspeed,

BO"