A former Danish prime minister has lashed out at US President Donald Trump for his tweet about military spending, saying defence willingness is not just about the amount of money spent.
Lars Loekke Rasmussen's comment is the latest in an escalating spat between the US and Denmark after Trump scrapped a visit to the country, saying current Prime Minister Mette Frederiksen was "nasty" when she rejected his idea of buying Greenland as an absurdity.
Loekke Rasmussen, who led the country until June, tweeted Thursday to Trump: "We have had (proportionally) exactly the same numbers of casualties in Afghanistan as US. We always stands firm and ready."
Trump, who has urged NATO members to do more to meet the alliance's goal of committing two per cent of gross domestic product to defense, earlier tweeted that "Denmark is only at 1.35%".
"We will not accept that our defense willingness is only about percentages," Loekke Rasmussen tweeted. "I told you at the NATO Summit in Brussels last year."
In January, Denmark agreed to increase its long-term defence spending after a coalition in Parliament agreed to add 1.5 billion kroner ($A329 billion) to the already agreed-upon defence budget for 2023, which would put defence spending at 1.5 per cent of gross domestic product for that year. The US spends about 3.4 per cent of its GDP on defence.
Trump abruptly cancelled his planned September 2-3 visit to Denmark on Tuesday, after Frederiksen had called Trump's idea to buy Greenland "an absurd discussion".
Trump said her comment "was nasty. I thought it was an inappropriate statement. All she had to say was say, 'No, we wouldn't be interested."'
Frederiksen said the US remains one of Denmark's close allies.
The political brouhaha over the world's largest island comes from its strategic location in the Arctic. Global warming is making Greenland more accessible to potential oil and mineral resources.
Russia, China, the US, Canada and other countries are racing to stake as strong a claim as they can to Arctic lands, hoping they will yield future riches.
Frederiksen has said that Denmark's doesn't own Greenland which belongs to its people. It is part of the Danish realm along with the Faeroe Islands, another semi-autonomous territory, and has its own government and parliament, the 31-seat Inatsisartut.
The scarely populated island which is four times zones behind Copenhagen, became a Danish colony in 1775 and remained that way until 1953, when Denmark revised its constitution and made the island a province.
In 1979, Greenland and its 56,000 residents who are mainly indigenous Inuits, got extensive home rule but Denmark still handles its foreign and defense policies, as well as currency issues.
Denmark which considers Greenland as an equal partner, pays annual subsidies of 4.5 billion kroner ($A986 million) to Greenland whose economy otherwise depends of fisheries and related industries.