The US president had claimed that allied soldiers stayed "off the front lines" in Afghanistan

US President Donald Trump should apologize for downplaying the role of America's allies in the war in Afghanistan, British Prime Minister Keir Starmer has said.

In 2001, the US invoked NATO's Article 5 after the 9/11 attacks, requiring member states to support the invasion of Afghanistan. Trump, however, has repeatedly accused the bloc's European members of neglecting their commitments to the US.

Speaking to Fox News in Davos, Switzerland, on Thursday, Trump argued that the US "never needed" any help and that America's NATO allies had "stayed a little back, a little off the front lines."

Starmer hit back on Friday, accusing the president of downplaying the contribution of British troops. "I consider President Trump's remarks to be insulting and frankly appalling, and I'm not surprised they've caused such hurt for the loved ones of those who were killed or injured," he told reporters.

Asked whether he would like an apology from Trump, Starmer said: "If I had misspoken in that way or said those words, I would certainly apologize."

Prince Harry, who served two tours in Afghanistan, said the sacrifices of British soldiers "deserve to be spoken about truthfully and with respect."

The UK provided the second-largest number of Western troops in Afghanistan, peaking at around 11,000 in 2011, according to the BBC. A total of 2,456 Americans and 457 Britons died over the course of the 20-year conflict.

European countries have been on edge since Trump renewed his threats to annex Greenland from Denmark. In Davos, Trump described the Nordic country as being "ungrateful" for US help in defeating Nazi Germany in World War II. Multiple states have warned that a potential US attack on a fellow NATO member would be a death knell for the bloc.