Italian Prime Minister Matteo Renzi leaves a European Union meeting in Brussels on Dec. 18. (Thierry Charlier/AFP/Getty Images)

— The European Union on Monday extended sanctions against Russia for six months, achieving consensus among the bloc’s 28 member nations despite rising divisions over how long to press a major trading partner over its annexation of Crimea and its role in Ukraine’s separatist war.

The decision, given preliminary approval by E.U. leaders last week and due to take effect Tuesday, lengthens until next year a laundry list of economic measures against Russia. In tandem with U.S. sanctions, the effort has contributed to a painful economic slowdown in Russia.

But amid growing grumbling from some European countries about the sanctions, the future of the punitive measures beyond this renewal remains unclear.

The decision to extend the sanctions comes at the end of a difficult year for the E.U., which has had to contend with terrorist attacks in Paris, the near-exit of Greece from the euro zone in July and a refugee influx that is forcing nations to make difficult choices about their values. None of the problems seems likely to abate next year, leaving open the question of whether European nations will continue to hold together on the sanctions.

The measures were imposed after Russia annexed Ukraine’s Crimean Peninsula in March 2014. They were strengthened after separatists in eastern Ukraine, backed by Russian firepower, downed Malaysia Airlines Flight 17 in July 2014 as it was flying from Amsterdam to Kuala Lumpur, Malaysia, killing all 298 people aboard. The United States and the European Union have linked any rollback of the sanctions to the implementation of a peace plan reached in Minsk, Belarus, that would hand full control of Ukraine’s border with Russia back to Kiev, a step that has not been taken.

“Since the Minsk agreements will not be fully implemented by 31 December 2015, the duration of the sanctions has been prolonged whilst the Council continues its assessment of progress in implementation,” the European Council announced in a statement Monday.

The sanctions will now be in place until the end of July .

But there is growing fatigue with the sanctions campaign among some E.U. countries, including Italy and France, which have long-standing trade ties to Russia in the energy sector. Italian Prime Minister Matteo Renzi last week delayed the extension of the sanctions until he could confront German Chancellor Angela Merkel about what he sees as a double standard. Germany and Russia this year announced plans to build a natural gas pipeline between them through the Baltic Sea, bypassing Eastern Europe.

Renzi has complained that Merkel has forced other E.U. nations to agree to the sanctions even though Germany has engaged in projects that contravene the spirit of the effort, if not the letter of the law. Italy, in particular, is bitter that the new German-Russian project, known as Nord Stream-2, comes after the cancellation of a different pipeline project, South Stream, that would have been constructed in partnership with Italy’s Eni energy company. Bulgaria, another country that was poised to gain from the South Stream project, also has complained about the sanctions.

“I have some different ideas with Angela about a lot of dossiers. First about Nord Stream. Because I think it’s incredible to stop South Stream just one year ago and then accept the Nord Stream,” Renzi said after meeting with E.U. leaders last week. He said that “for the first time,” Germany was not in a majority on the issue in the closed-door meetings.

Merkel has tried to play down the differences, as well as the political implications of the German-Russian energy project.

“This is first and foremost a business proposition,” Merkel said of Nord Stream-2, speaking to reporters after the E.U. meetings. “Italy would have loved to participate in South Stream, which is very clear. Bulgaria also raised its voice.”

Battered by an influx of refugees from the conflict in Syria, European leaders have sought to make Russia a partner in the effort to stop the civil war there after it began bombing rebel and militant positions in September. Some leaders have sought to link progress in Syria with a rollback of the sanctions over Ukraine, diplomats say, an effort that the United States strenuously opposes.

The sanctions have drawn complaints from Russian President Vladimir Putin, who said Sunday that Europe was simply acting as an extra arm of the United States.

Europe “does not pursue an independent foreign policy at all. It has essentially abandoned it,” he said in a documentary broadcast Sunday on the state-run Rossiya-1 channel.

Russia’s economy has been flagging, hit by the combined wallop of sagging oil prices and sanctions. Inflation has soared, hitting the pocketbooks of ordinary citizens and prompting rising complaints about the direction of the country. Putin’s popularity remains high, though, with 85 percent of Russians holding a favorable opinion of him, according to the latest figures from the independent Levada Center.