The EU's effort to thwart U.S. President Donald Trump's Iran sanctions is open for business.

France, Germany and the U.K. — the European guarantors of the Iran nuclear accord — announced Thursday that they have officially established a corporate "special purpose vehicle," registered in Paris, to help European companies that want to continue doing business with Iran despite Trump's renewed sanctions.

The corporate vehicle will facilitate business deals with Iran without using the dollar or the U.S. financial system and will essentially structure sales as indirect transactions — steps that the Europeans believe will technically avoid violations of the U.S. sanctions.

The special purpose vehicle is called INSTEX, for Instrument in Support of Trade Exchanges. It had been in development for months, since shortly after Trump last May declared the unilateral U.S. withdrawal from the nuclear accord, called the Joint Comprehensive Plan of Action (JCPOA).

The official announcement was made by French Foreign Minister Jean-Yves Le Drian, German Foreign Minister Heiko Maas and British Foreign Secretary Jeremy Hunt in Bucharest, Romania where they were attending a meeting of EU foreign and defense ministers.

Russia and China have also stuck with the accord despite Trump's withdrawal.

The establishment of the special purpose vehicle is the most visible and substantive rebuke of Trump's foreign policy by European allies that have disagreed with many of the American president's decisions, including his withdrawal from the Paris climate accords and his relocation of the U.S. Embassy in Israel to Jerusalem from Tel Aviv.

Washington said it is still examining the new entity but issued a stern warning against violating U.S. sanctions.

"Entities that continue to engage in sanctionable activity involving Iran risk severe consequences that could include losing access to the U.S. financial system and the ability to do business with the United States or U.S. companies," the State Department said in a statement.

INSTEX was registered in Paris using the address of the French Ministry of Economy and Finance. France, Germany and the U.K. are joint shareholders and the entity's president is Per Fischer, a veteran German banker who spent many years as a senior executive of Commerzbank.

It is not clear how many businesses will make use of INSTEX and tempt the wrath of the Trump administration. Many are loath to risk losing access to the far larger and more lucrative U.S. market in order to maintain far less profitable dealings with Iran.

But even if it gets limited use, the creation of INSTEX is an important symbolic step, providing concrete evidence to Iran of Europe's continued commitment to the JCPOA. Russia and China have also stuck with the accord despite Trump's withdrawal.

Many experts believe that the key to preserving the JCPOA is maintaining Tehran's commitment and the creation of INSTEX potentially helps answer Iranian critics who have been urging the government to withdraw in response to Trump. In Europe, the hope is that Tehran will hold on long enough for Trump potentially to be voted out of office.

The EU and the European powers insist that Tehran has been living up to its commitments under the agreement, citing 13 reports by the International Atomic Energy Agency.

Separately, the EU has taken steps to punish Tehran over allegations of military meddling throughout the Middle East and at least two assassination attempts on European soil. But the EU has insisted that those issues should not be conflated with the JCPOA, which they say has successfully halted Iran's nuclear weapons program.

"The lifting of sanctions is an essential dimension of the JCPOA," the EU's high representative for foreign affairs, Federica Mogherini, said in a statement praising the creation of INSTEX. "The instrument launched today will provide economic operators with the necessary framework to pursue legitimate trade with Iran."

"The European Union continues to be committed to the full and effective implementation of the JCPOA in all its aspects as long as Iran continues to implement in full all its nuclear commitments, as set out by the agreement," Mogherini said, adding: "This is a matter of respecting international agreements and of advancing our shared regional and international security."

"Today we have taken a significant step forward in delivering our commitment under the Iran nuclear deal to preserve sanctions relief for the people of Iran," Hunt, the British foreign secretary, said in Bucharest. “This is a clear, practical demonstration that we remain firmly committed to the historic 2015 nuclear deal struck with Iran."