WASHINGTON, United States (AFP) — US President Donald Trump denied stoking racial tensions Monday, insisting his charged comments that prompted a wave of symbolic protests by NFL players were about patriotism.

After his verbal attacks on black athletes led players across the country to kneel in solidarity during the US national anthem at games over the weekend, the besieged US president played defense on Twitter.

Trump had sparked the furore by describing NFL players who chose to take a knee through renditions of “The Star-Spangled Banner” as “sons of bitches” who should be fired.

Players throughout America’s most popular sport took a defiant stance, kneeling, linking arms or raising clenched fists during the anthem.

The US leader doubled down on those remarks by urging fans to boycott the NFL as long as the protests continued.

Keeping the issue alive for a fourth day, Trump on Monday insisted “The issue of kneeling has nothing to do with race. It is about respect for our Country, Flag and National Anthem. NFL must respect this!”

More than 150 players could be seen kneeling or sitting in the 14 games that took place Sunday, easily the largest such demonstration since former San Francisco 49ers quarterback Colin Kaepernick first began protesting in 2016.

One of the biggest protests took place in the nation’s capital, where almost the entire line-up of the Oakland Raiders team sat on their bench ahead of their game with the Washington Redskins. Trump — who faces low poll numbers and is struggling to enact his agenda — on Monday tried to single out the NFL players who protested.

“Many people booed the players who kneeled yesterday (which was a small percentage of total). These are fans who demand respect for our Flag!” he tweeted.

He pointed to support from race car fans.

“So proud of NASCAR and its supporters and fans. They won’t put up with disrespecting our Country or our Flag – they said it loud and clear!”

But driver Dale Earnhardt took to Twitter to quote former president John F Kennedy: “All Americans R granted rights 2 peaceful protests Those who make peaceful revolution impossible will make violent revolution inevitable.”

On Saturday, Trump had also drawn a furious backlash from NBA stars after stating on Twitter that the champion Golden State Warriors and star Stephen Curry would not be invited to attend a White House reception.

Trump has whole-heartily embraced the controversy, with his advisors believing it plays well with his largely white base.

Trump also changed his Twitter background photo to an American flag and stated that the “White House never looked more beautiful than it did returning last night.”

Critics accuse Trump of creating a diversion.

His efforts to repeal Barack Obama’s healthcare reforms have run aground and would-be signature tax reforms are giving way to much less ambitious tax cuts.

At the same time Trump faces a number of challenges from overseas, not least a war of words with North Korea that threatens to become a shooting war.

North Korea in recent weeks detonated its sixth nuclear bomb and has test-fired intercontinental missiles — saying it needs to defend itself against hostility from the United States and its allies.

Addressing the UN General Assembly last week, Trump responded by calling leader Kim Jong-Un a “Rocket Man” on a “suicide mission,” prompting Kim to warn in turn that the US president would “pay dearly” for his threat.

Escalating tensions further, North Korea’s foreign minister said Monday that Trump had “declared a war” on North Korea, while conveying a threat to shoot down US bombers.