WASHINGTON -- President Donald Trump on Saturday night stoked the controversy over his call for punitive action against NFL players who take a knee or otherwise protest during the national anthem, tweeting anew that they should remain standing out of respect for the nation and its flag.

Trump took time from a Twitter rant against criticism of the federal response to hurricane damage in Puerto Rico to tweet.

"Very important that NFL players STAND tomorrow, and always, for the playing of our National Anthem. Respect our Flag and our Country!" he tweeted.

Very important that NFL players STAND tomorrow, and always, for the playing of our National Anthem. Respect our Flag and our Country! — Donald J. Trump (@realDonaldTrump) September 30, 2017

He later added, alongside a video: "19,000 RESPECTING our National Anthem! #StandForOurAnthem."

Protesting during the playing of "The Star-Spangled Banner" began last season when Colin Kaepernick, then a quarterback with the San Francisco 49ers, declined to stand as a way to bring attention to police treatment of blacks and to social injustice.

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During a wide-ranging speech at a political rally in Alabama on Sept. 22, Mr. Trump called for NFL owners to fire players who engaged in such a protest. In the days that followed, the president issued a series of tweets reiterating his views and calling for a boycott of games by fans.

Criticism from players, owners and fans -- and some praise -- greeted Mr. Trump's remarks. The controversy boiled for days and seemed to overshadow other issues facing the Trump presidency, including the failure of congressional Republicans to repeal and replace the nation's health care law, the primary loss in Alabama of Mr. Trump's favored candidate, a turbulent hurricane season and the back-and-forth between the U.S. and North Korea over missiles and nuclear weapons.

Relatively few players had demonstrated before Mr. Trump's remarks. Last Sunday, more than 100 NFL players sat, knelt or raised their fists in defiance during the national anthem.