HELSINKI — Once a timid and compliant member of the European Union, Finland has become one of its most rebellious.

The Finns have made headlines recently by threatening to pull out of a rescue plan for debt-stricken Greece and blocking Romania and Bulgaria from joining Europe's passport-free travel zone.

The Nordic nation's dwindling enthusiasm for European integration challenges the cohesion of the 27-nation bloc as it struggles to tackle the debt crisis.

"Finland is stepping out of line. It's very clearly a new phenomenon," said Jan Sundberg, professor of political science at the University of Helsinki.

The country of 5 million on the EU's northeastern border has traditionally been more pro-EU than Nordic neighbors Denmark and Sweden and is the only country in the region to have adopted the euro as its currency.

But Finland's affection for Europe is waning, with a survey showing that satisfaction with the EU has dropped to 37 percent earlier this year from 42 percent in 2005. Finnish business and policy forum EVA interviewed 1,918 people for the poll in January and February. It had a margin of error of 1-2 percentage points.

In April elections, the euroskeptic and populist True Finns party — which has since changed its name to The Finns — made strong gains in April elections to become the country's third largest political group.

"Finland is seen as a troublemaker now. It's a looming, increasing lack of solidarity with the European project," said Marlene Wind, head of European politics at Copenhagen University. "If this spreads we'll have a huge problem getting Europe back on track."

After the election, Europe watched Finland's government formation talks with grave concern, fearing The Finns would be included and stop Finland's participation in eurozone bailouts for Greece and Portugal.

Conservative Prime Minister Jyrki Katainen in the end formed a coalition government without The Finns, but with four others, including two euroskeptic parties.

In May, Parliament approved Finnish participation in the Portugal bailout on condition that Finland be granted guarantees, or collateral, for its share of any future eurozone loans.

Last month, Finland and Greece announced they had agreed on such guarantees for Finland's share of the Greek bailout but leading eurozone members, including Germany, insisted the 17-member currency union would jointly decide the collateral issue.

They said talks would continue with all eurozone members until a joint solution was reached.

Katainen, who is staunchly pro-EU, worried the collateral issue would tarnish the country's reputation.

"To be honest, this will leave a mark," Katainen said in a radio interview earlier this month. "But I believe it will be temporary and small, if we find a solution to the guarantees that won't upset the stability of the euro and damage other eurozone members."

Nevertheless, he is adamant that Finland will not back down from its collateral demand, or it will opt out of the Greek aid package.

To some extent the shift in attitudes can be traced to Finland's maturity and self-confidence as an independent nation. Through most of its history it's been occupied by its neighbors — for 600 years by Sweden and between 1812 and 1917 by Russia, with which it shares an 800-mile (1,300-kilometer) border.

It walked a precarious tightrope during the Cold War as a neutral country, submitting foreign policy decisions for Kremlin's tacit approval in exchange for its independence.

When the Soviet Union collapsed, Finland jumped at the opportunity to cement ties with the West, joining the EU in 1995 after a referendum in which a clear majority — 57 percent — voted in favor of membership.

But the perceived threat from Russia gradually subsided, while Finland's economy emerged as one of the most stable and well-off in the EU. With Greece and Portugal needing EU bailouts, Finland's inferiority complex toward Europe has given way to a sense that it's being forced to pay for the financial missteps of other countries, including Greece and Portugal.

This sentiment is spearheaded by The Finns party.

"It's about time that we're able to talk openly about issues that matter, and our Finns party has done just that," said Toni Paussu, a 41-year-old tour operator who voted for The Finns. "At first we were labeled as swimming against the tide, but no longer. People listen to us now and others too have the courage to speak their mind."

Last week Finland challenged the authority of Brussels once again, joining the Netherlands in blocking entry by the EU's newest members, Romania and Bulgaria, to the borderless "Schengen" zone, saying they needed to do more to fight corruption and organized crime.

"We are not being difficult," Katainen insisted. "Our aim is to make sure that countries that have problems ... put them in order before they are accepted into the Schengen zone."

Simon Tilford, from the London-based Center for European Reform, said he is baffled by Finland's rebel stance on the collateral issue, but doesn't believe that it will inspire many others to do the same.

"I think there is a risk of the smaller members, Slovakia and a couple of others maybe attempting that, but the diplomatic and political pressure not to do so will now be very, very fierce," he said. "It's very hard to imagine any of the key governments opting for that route. If it was the Netherlands or Germany or France it would bring the whole thing down overnight."

Tilford said he expects Finland to be forced to a compromise because countries like Germany and the Netherlands "cannot afford for Finland to be allowed to be seen to free-ride on the back of their painfully wrought guarantees."

Tilford says that Finland knew what it was getting into when it adopted the euro in 2002. "Finland has made its bed, it's gotta lie in it," he said.