Donald Trump entering the White House could change America’s relationship with the rest of the world in some important ways. Here are seven of them.
Nato faces a shake-up
Mr Trump has been hugely critical of Nato (the North Atlantic Treaty Organization), a cornerstone of American foreign policy for more than 60 years.
He has attacked the organisation as obsolete and characterised its members as ungrateful allies who benefit from US largesse.
Days before his inauguration, he reiterated that “a lot” of Nato’s 28 member states were not paying their fair share, which was “very unfair” to the US.
The latest rebuke came as 3,000 US troops arrived in Poland as part of Barack Obama’s plans to reassure Nato allies concerned about perceived Russian aggression.
In one sense, Mr Trump’s rhetoric simply gives voice to longstanding US concerns about most Nato members not meeting their goal of spending at least 2% of GDP on defence, while US defence spending is the largest in the world.
The president-elect also stressed that Nato was “very important” to him.
But that provided little comfort and his stance has sparked alarm in Europe. Germany’s foreign minister said Mr Trump’s comments were causing “worry” in the alliance.
New cosier ties with Russia?
During the US election campaign, Mr Trump praised Russian President Vladimir Putin as a strong leader, with whom he would love to have a good relationship.
That was before US intelligence agencies determined Russia was responsible for hacking Democratic Party emails during the campaign – a conclusion that President-elect Trump has finally conceded he agrees with.
The explosive publication of an unverified dossier alleging that Russia holds compromising material on Mr Trump has also raised new, prickly questions for the president-elect.
He has batted them away, dismissing the allegations as “fake news” and questioning if the dossier was purposely released by intelligence operatives.
Now Mr Trump says he will start off trusting Mr Putin (and German Chancellor Angela Merkel) but warns “it may not last long at all”.
He also says he will keep US sanctions on Russia “at least for a period of time”.
But he suggested in an interview that international sanctions could be lifted if some “good deals” can be made with Russia, including on nuclear arms reduction.
US-Russia relations have become significantly strained over the course of the Obama administration over Ukraine, Syria and cyber-hacking. This appears to be a bilateral relationship where the dynamics could change significantly under President Trump.
An end to free trade?
Donald Trump’s trade policies would amount to the single biggest change to the way America does business with the rest of the world in decades.
He has threatened to scrap a number of existing free trade agreements, including the North American Free Trade Agreement between the US, Canada and Mexico, which he blames for job losses. He has even suggested withdrawing the US from the World Trade Organization.
Since winning the election, he has focused on threatening companies, particularly automobile makers, that he will slap a tariff of 35% on goods manufactured in Mexico.
The thrust behind his trade policy will be to create jobs in the US, close the trade deficit, and get “good deals” for Americans.
China, in particular, is in the crosshairs, and not just on trade.
An end to the One China policy?
A phone call between Mr Trump and Taiwan’s President Tsai Ing-wen in early December broke four decades of US protocol.
Beijing sees Taiwan as a province, and denying it the trappings of an independent state is a key priority of Chinese foreign policy, something the US has recognised with its longstanding “One China” policy.
The incoming president recently said that “everything is under negotiation, including One China”. China responded by saying the principle was non-negotiable.
These conflicting positions raise serious questions for the trajectory of the relationship between the world’s two largest economies going forward.
But Mr Trump is showing a degree of pragmatism on other China-related issues. He has backed away from a previous pledge to label China a currency manipulator when he takes office. He now says he will “talk to them first”.
Iran nuclear accord could be rethought
For President Obama, the deal that saw sanctions against Iran lifted in exchange for guarantees it would not pursue nuclear weapons was a “historic understanding”.
But for Donald Trump, echoing Republican concerns, it was “the worst deal I think I’ve ever seen negotiated”.
He had said dismantling it would be his “number one priority” but now says he doesn’t want to specify what he will do.
“Who plays cards where you show everybody the hand before you play it?” he said in an interview with the Times.
Getting rid of the deal would have a huge impact on the Middle East. Iran is a key player in the Syrian conflict and a rival of Saudi Arabia and Israel, for instance.
Already Iran’s Foreign Minister Javad Zarif has urged Trump to stay committed to the nuclear deal. He suggested the US would have to respect the accord given that it was thrashed out with several world powers.
Iranian Supreme Leader Ayatollah Ali Khamenei was more blunt. “If they tear it up, we will burn it,” The Associated Press quoted him as saying.
More nuclear weapons in Asia?
A Donald Trump presidency raises major security questions in Asia.
Not only has the president-elect shocked China with comments on Taiwan, but his secretary of state nominee Rex Tillerson has spoken of blocking China’s access to artificial islands it has been building in the South China Sea, prompting warnings of a “military clash” from a state-run newspaper.
Japan and South Korea have both been singled out by Mr Trump for relying too much on the US. He has even said they would benefit from having their own nuclear arsenals.
Then there is the region’s renegade state, North Korea, which is currently developing its own nuclear weapons.
Mr Trump faces the task of curbing those ambitions, something that has eluded successive US leaders.
How he might do this is unclear but he has proposed negotiating directly with North Korean leader Kim Jong-un.
In response to a recent announcement from Mr Kim that North Korea was close to testing long-range missiles capable of carrying nuclear warheads, Mr Trump simply tweeted : “It won’t happen.”
Whether he has a strategy in mind is unknown, but US politics’ most unpredictable presidential candidate tackling the world’s most unpredictable state makes North Korea a likely flashpoint in the coming years.
Climate change revamp
President-elect Trump has said that he will “cancel” the Paris Climate Agreementwithin 100 days of taking office and will do everything in his power to reverse climate change regulations introduced by President Obama.
Mr Trump has repeatedly denied the science of human-caused climate change, describing it as “fictional’.
Like many issues, however, he has expressed conflicting views, telling the New York Times in November that he acknowledged there was “some connectivity” between human activity and climate change and saying he would “take a look at” the Paris agreement, rather than having already decided to pull the US out of it.
Even if he wanted to do that though, the US remains legally bound to the Paris plan for four years. There are also “legal and procedural roadblocks” which would inhibit Mr Trump from a complete overhaul of US climate policy, The New York Times says.
Critics say his stance could cause other reluctant governments sceptical about the issue to reduce their efforts to cut planet-warming emissions.
The president-elect’s plans to renege on the Paris Agreement, his disdain for President Obama’s Clean Power Plan and his determination to push forward with coal have been condemned by green groups globally.
But fossil fuel supporters say Mr Trump’s plans prioritise the needs of American families by delivering them affordable energy in addition to invigorating the economy and creating more opportunities for future generations.