UK fans began chanting "leave Greenland alone" and booing the US national anthem during the London NBA game between the Memphis Grizzlies and the Orlando Magic.
Before the game was about to begin, X-rated language, including "f**k ice", was heard around the O2 Arena.
The game marks the NBA's return to London for a regular-season game for the first time since 2019.
This match concludes a two-game European tour for both sides, forming part of a three-year international programme that will see NBA action in Manchester and Paris next year, followed by Berlin and Paris in 2028.
The contest represents the 19th game featuring an NBA team in the United Kingdom since 1993.
Key players expected for the Grizzlies, currently 11th in the West, include Ja Morant (probable) and Jaren Jackson Jr., while the 5th-place Eastern Conference Magic feature Paolo Banchero and the Wagner brothers, Franz and Moritz.
It comes amid tension between the UK and the US over Donald Trump's ambitions to take control of Greenland.
Mr Trump announced his plans to implement a 10 per cent tariff on European countries that opposed the move in a lengthy post on his Truth Social platform yesterday.
UK fans began chanting 'leave Greenland alone' and booing the US national anthem during the London NBA game
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The post read: "Starting on February 1, 2026, all of the above mentioned countries (Denmark, Norway, Sweden, France, Germany, The United Kingdom, The Netherlands, and Finland), will be charged a 10 per cent tariff on any and all goods sent to the United States of America.
"On June 1, 2026, the tariff will be increased to 25 per cent. This tariff will be due and payable until such time as a deal is reached for the complete and total purchase of Greenland."
European countries threatened by Donald Trump's tariffs for not backing the US President on Greenland have issued a statement.
The joint message by Denmark, Finland, France, Germany, the Netherlands, Norway, Sweden and the UK said: "We stand in full solidarity with the Kingdom of Denmark and the people of Greenland."
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The Memphis Grizzlies and the Orlando Magic are playing at the O2
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They added: "Tariff threats undermine transatlantic relations and risk a dangerous downward spiral. We will continue to stand united and coordinated in our response.
"We are committed to upholding our sovereignty. As members of Nato, we are committed to strengthening Arctic security as a shared transatlantic interest.
"The pre-coordinated Danish exercise 'Arctic Endurance' conducted with allies, responds to this necessity. It poses no threat to anyone."
The US President vowed to implement a wave of increasing tariffs until the US is allowed to purchase Greenland.
British exporters are facing a £6billion blow after President Donald Trump imposed a new 10 per cent tariff linked to Greenland | GETTYSir Keir Starmer previously stated that the future of Greenland should be determined solely by the residents of Greenland and Denmark.
The Prime Minister conveyed his stance on Greenland to Mr Trump during a phone call earlier this month, which was described as friendly and positive.
Conservative Party leader Kemi Badenoch described the move by the US President as "completely wrong", writing on X: "A terrible idea. President Trump is completely wrong to announce tariffs on the UK over Greenland.
"People in both UK and US will face higher costs. These tariffs will be yet another burden for businesses across our country. The sovereignty of Greenland should only be decided by the people of Greenland. On this, I agree with Keir Starmer."
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