Voters in Iceland went to the polls Saturday to decide whether the country should resume long-stalled negotiations to become a member of the European Union, in the shadow of U.S. President Donald Trump's threats to control nearby Greenland.

The yes-or-no referendum question is simple enough for the 265,000 or so eligible voters: Should Iceland resume accession negotiations with the European Union?

A yes vote would trigger negotiations with the EU's executive branch, the European Commission, covering 35 areas, from the economy to human rights. Some supporters believe the European Union could offer protections if Trump ever made similar threats against Iceland. They also see economic stability in joining the bloc.

If voters reject the proposal, that's it, for a generation at least. Opponents have rallied around the threat EU membership would pose to Iceland's rich fishing stocks and the fact that Iceland already reaps benefits from being in the EU's frictionless single market and the Schengen free-travel zone.

Experts expect a close vote.

More than 20% of voters cast early ballots in advance of election day, Iceland's national broadcaster RÚV said.

Nearby Greenland casting a shadow over referendum

When Trump talked about U.S. control of Greenland, particularly at the start of this year, he shifted the mood in Iceland, just 180 miles (290 km) from the self-governing territory of Denmark, a longtime U.S. ally. Some Icelanders were particularly alarmed when he mistakenly named their country four times while speaking about his designs on Greenland.

Though Trump has indicated he won't use force to seize Greenland, his interest doesn't appear to have cooled.

The underlying worry among many in Iceland is clear - if Greenland is seized, is Iceland next?

The ensuing question is clear too: if yes, does EU membership provide a bulwark against any new Trump ambition in the North Atlantic?

Iceland's left-leaning coalition government, elected in 2024, certainly thinks so, and that's largely why it moved forward with the EU referendum that it had planned for next year.

"We can't really trust the U.S. anymore," said Hildur Knútsdóttir, a horror fiction writer who plans to vote in favor of EU membership.

After more than a decade, EU membership is back on the agenda

EU talk is nothing new in Iceland, which formally ended its previous effort to join the bloc in 2015, largely over concerns of what membership would mean for its rich fish resources.

The hefty cod and haddock catches from the chilled Arctic waters around Iceland are central to the national identity too. Descendants of Vikings who settled in Iceland have lived off the sea for centuries.

With much of the country's economy geared toward its lucrative and well-managed fishing industry, fishing rights have been a talking point in the run-up to the referendum.

Joining the 27-nation EU would require Iceland to be part of the bloc's common fisheries policy that would allow Spanish, Dutch and other trawlers into its waters. The government has indicated it would seek a special arrangement, potentially a full opt-out from the policy.

In the final days ahead of the vote, Iceland's prime minister, Kristrún Frostadóttir, has sought to remind voters that the referendum is not the end of the matter, and that there will be another referendum if and when Iceland reaches a membership agreement with the EU.

"This is not an election about membership and not about adaptation, as there will be another referendum on an accession agreement if the result is yes," Frostadóttir told a rally.

Fish is not just an economic matter; it's part of the national identity

For many, Iceland's national identity and ultimately its culture is on the ballot too.

Iceland, which gained independence from Denmark in 1944, has a proud history of refusing to be pushed around by bigger and richer European nations. It even fought - and won - the so-called Cod Wars with Britain in the 1970s over its fishing grounds.

Backers of EU membership say it's best for Iceland to get closer to its European neighbors to combat issues that don't respect borders, such as climate change. They also say the euro would bring more stability than Iceland's volatile króna currency.

Opponents say the current setup is just right and that Iceland already enjoys all the benefits of European integration without the sovereignty compromises that inevitably come with full membership. They cite trade deals, such as one with China, that are more favorable.

"I think Iceland is better off outside of the EU, within the close collaboration with the EU," former prime minister, Katrín Jakobsdóttir, told The Associated Press.