WASHINGTON President Donald Trump is angry at Sen. John McCain (R-Ariz.) for indirectly criticizing him in a speech Monday.

People have to be careful because at some point I fight back, Trump told radio station WMAL on Tuesday. Im being very nice. Im being very, very nice. But at some point I fight back, and it wont be pretty.

McCain, a former prisoner of war, had lambasted half-baked nationalism in a Monday night speech that didnt mention the president by name but described the presidents foreign policy agenda.

To fear the world we have organized and led for three-quarters of a century, to abandon the ideals we have advanced around the globe, McCain said, for the sake of some half-baked, spurious nationalism cooked up by people who would rather find scapegoats than solve problems is as unpatriotic as an attachment to any other tired dogma of the past that Americans consigned to the ash heap of history.

McCain also said we live in a land made of ideals, not blood and soil a reference to the blood and soil chants used by Nazis during a violent August protest in Charlottesville, Virginia. Trump had said there were very fine people among the Nazis.

Its not clear what leverage Trump thinks he has over McCain, to whom he hasnt been nice since he ridiculed the senator in July 2015 for having been captured during the Vietnam War. McCain spurned Trump in July and again in September by opposing Republican health care legislation, leaving Trumps legislative agenda in shambles.

I have faced some pretty tough adversaries in the past, McCain told reporters Tuesday. Im not interested in confronting the president, Im interested in working with the president.

Igor Bobic contributed reporting.

Arthur Delaney hosts the HuffPost Politics podcast: