Royal Dutch Shell PLC on Wednesday said it had signed a memorandum of understanding with Iran’s state oil company to explore future ventures, signaling that giant energy companies won’t be deterred by President-elect Donald Trump’s pledge to undo the Iran nuclear deal.

Shell is the largest company to wade back into Iran since the U.S. and other world powers lifted sanctions in January in exchange for Tehran’s agreement to strict limits on its nuclear program. The British-Dutch firm follows Total SA of France, which last month signed a $4.8 billion deal to develop a large gas field in Iran and is negotiating for an oil deal now.

The scope of the deal remained unclear Wednesday. A Shell spokesman said Shell and the National Iranian Oil Co. signed an understanding to “further explore areas of potential cooperation.” The agreement is non-binding and doesn’t come with an investment commitment, unlike the recent agreement Total concluded with Tehran.

Earlier on Wednesday, the Iranian oil ministry had said Shell was going further, signing agreements to develop two giant oil fields that are important to the future of the country’s oil industry.

The return of Shell would be a breakthrough for Iran’s energy industry, which has been slow to attract investments from the world’s biggest oil companies since the U.S. and other world powers lifted sanctions related to Tehran’s nuclear program. The continued existence of separate U.S. sanctions on Iran over terrorism, human rights and weapons has impeded investment, while oil companies in particular are concerned with the terms Iran wants to impose on foreign companies.