The wording seems correct to me. The US is changing its entry requirements. While you may not need a passport to enter another country, you will soon need one to come back to the US -- even if you are a US citizen.
This article has some information. Some of it is as follows:
...Americans who can now leave the country without a passport if their destination does not require one, such as travel by land to Canada or Mexico, will need a passport to get back into the United States starting this December. Showing a driver's license or a government-issued photo ID card will no longer be sufficient for making the border crossing back.