US President Donald Trump has said he no longer feels obliged to think only of peace after he was not awarded the Nobel Peace Prize last year, BBC reports.
In a message to Norway's Prime Minister Jonas Gahr Støre, Trump blamed the country for not giving him the prize.
In his reply to Trump, Støre explained that an independent committee, not the government of Norway, awards the prize which last October went to Venezuela's opposition leader María Corina Machado.
In the same message to Støre, Trump insisted the US needed "Complete and Total Control of Greenland" - the semi autonomous Danish territory. Asked later if he planned to use force to seize it, he replied "no comment".
Denmark is a fellow member of Nato - a defence alliance with the US as its most influential partner. It works on the principle that members should defend each-other in case of external attacks.
There has never been an attack by one member against another since the alliance was founded in 1949.
Denmark has warned that US military action in Greenland would spell the end of Nato. It has received support from European members of the alliance - some even sent a handful of troops to Greenland last week in a move seen as symbolic.
However, Trump followed that deployment with an announcement to impose a 10% tariff on goods from eight Nato allies - including the UK - from 1 February if they opposed his proposed takeover of Greenland, and threatened to raise it to 25% by June.
It was in this context of heightened tension that Jonas Støre sent a message to Trump on behalf of himself and the Finnish President, Alexander Stubb.
The two European leaders said "we all should work to take this down and de-escalate - so much is happening around us where we need to stand together".
In his reply, Trump wrote: "Considering your Country decided not to give me the Nobel Peace Prize for having stopped 8 Wars PLUS, I no longer feel an obligation to think purely of Peace, although it will always be predominant, but can now think about what is good and proper' for the US."
He went on to say that Denmark could not protect Greenland from Russia or China, and questioned, "why do they have a "right of ownership" anyway? There are no written documents, it's only that a boat landed there hundreds of years ago, but we had boats landing there, also".
"I have done more for NATO than any other person since its founding, and now, NATO should do something for the United States," he said.
"The World is not secure unless we have Complete and Total Control of Greenland," he concluded.
The sparsely populated but resource-rich Arctic island is well placed for early warning systems in the event of missile attacks and for monitoring vessels in the region.
