President-elect Donald Trump’s unexpected victory brings with it the potential to radically alter the United States’ role in global affairs and how it applies power. After a campaign in which Trump railed against generations of U.S.-built institutions and alliances, the world now waits to see whether his rhetoric becomes a reality.

Much of Trump’s stated foreign policy plans involve the U.S. pulling back or altering its commitments abroad. He has wavered in support for NATO, saying that members must pay more to the organization if they want U.S. military protection. He has criticized plans to increase U.S. involvement in Syria and characterized some of the fight against Syrian President Bashar Assad as a lost cause. Trump has also pledged to scrap or renegotiate major trade and nuclear deals.

Currently, it’s unclear how much Trump is posturing ― not to mention how much of his proposals are actually achievable ― but the looming uncertainty of U.S. foreign policy has officials around the world scrambling to prepare for what comes next.

Relations With Syria And Russia

Some of the largest shifts in policy from President Barack Obama’s administration could involve relations with Russia and their effect on European allies and the Syrian war. Trump has voiced admiration for Russian President Vladimir Putin and promoted renewed ties with Russia ― which the Kremlin hopes that will mean reduced economic sanctions and a freer hand to exert its power abroad.

The prospect of Trump’s presidency leading to an emboldened Russia has many of the United States’ NATO allies, especially in Baltic states, extremely worried. Trump has seemingly offered only conditional support for NATO’s Article V, which holds that an attack on any member state is an attack on all. Following the election, Baltic leaders issued statements hoping that the security commitments the U.S. has honored since 1949 will still be upheld.

The notion that U.S. allies have been getting a free ride has been a consistent part of Trump’s campaign, and may force longstanding regional partners like Japan and Saudi Arabia to reassess their security situations. Japanese Prime Minister Shinzo Abe will meet Trump next week to stress the issues of mutual cooperation and defense.

Trump is also unlikely to escalate U.S. involvement in Syria, where Russia has supported Assad’s regime with devastating airstrikes on rebels and civilians. Instead, Trump has said that Assad and Putin could help promote U.S. interests because they are attacking the self-described Islamic State.

Analysts have rejected this idea, pointing out that Russian and Syrian airstrikes largely target non-ISIS forces and that Assad’s military avoidance of the extremist group played a significant role in its rise.

Joshua Roberts/Reuters President-elect Donald Trump meets with House Speaker Paul Ryan (R-Wis.) and Vice President-elect Mike Pence.

The Paris Climate Agreement

One of the most significant and attainable of Trump’s professed policy positions concerns the landmark Paris climate agreement to cut global emissions, which took effect last week. Trump has repeatedly said that climate change is not a priority for the United States and has often referred to it as a hoax. During a campaign speech in May, Trump vowed to “cancel” the climate agreement and reverse Obama’s environmental initiatives.

If Trump decides the U.S. should exit the agreement, it would be well within his power to do so. As president, he could issue an executive order to trigger a U.S. exit from the deal on his first day in office. Provisions in the agreement require states to legally comply with the deal for four years after opting to withdraw, but it’s possible Trump could find ways to circumvent that.

A U.S. exit from the deal would destabilize the Paris agreement and the effort to present a unified, international effort to combat climate change. It could also mean states will be less likely to cooperate with the U.S. on future deals. The effect on the environment would be dire, experts say, and do irreparable damage to the earth’s climate.

Security And Trade Deals

Another key agreement that Trump’s presidency puts in danger is the Iran nuclear deal. The agreement to limit Iranian nuclear capabilities in exchange for sanctions relief is something Trump has called a “disaster” and promised to “dismantle” or renegotiate. As opposed to the Paris climate agreement, the Iran deal is more complicated for Trump to undo. The deal was a multilateral agreement that would require the cooperation of Russia, China and other states to renegotiate. A U.N. Security Council resolution also confirmed the deal.

Trump’s administration could break the terms of the deal, however, which would allow Iran to back out of the agreement and blame the United States. The confusion over exactly how Trump plans to approach the deal is one of the largest questions surrounding his incoming administration.

But while the Paris and Iran deals hang in limbo, the fate of the Trans-Pacific Partnership trade agreement is much more certain. Trump heavily opposes the already divisive deal, and Congress is also unlikely to vote to approve it.

Toby Melville/Reuters British newspapers had varied editorial reactions to Donald Trump's victory in the U.S. presidential election.

A European Divide Over Trump

In response to Trump’s victory, European foreign ministers are convening an emergency meeting on Sunday to discuss how Trump’s policies could affect trade, security and international relations.

Trump’s administration, unlike Obama’s, will likely do little to bolster the European Union and its institutions. In their letter of congratulations to Trump, European Commission President Jean-Claude Juncker and European Council President Donald Tusk called for a U.S.-EU summit to be held as soon as possible. For the pro-EU officials and liberal institutionalists who run the 28-member trade bloc, Trump represents a dangerous unknown.

“We would like to know what intentions he has regarding the [NATO] alliance. We must know what climate policies he intends to pursue. This must be cleared up in the next few months,” Juncker said on Thursday.

On the other side of the political spectrum, Trump’s victory has already inspired many far-right populist parties in Europe that have been growing with anti-EU and anti-immigrant sentiment. Among Trump’s biggest foreign backers are politicians such as Dutch anti-Islam politician Geert Wilders and French National Front Party leader Marine Le Pen. Le Pen has already hailed the U.S. election result as part of a “great movement across the world.”