Clean-power giant NextEra Energy Inc. is asking the U.S. Commerce Department to either force an anonymous group of U.S. solar manufacturers to identify its members or throw out their requests to extend tariffs on imported panels.

In a letter Tuesday to Commerce Secretary Gina Raimondo, Florida-based NextEra challenged applications filed last week by the so-called American Solar Manufacturers Against Chinese Circumvention, which seeks to extend import duties to certain Chinese-owned factories in Vietnam, Malaysia and Thailand. Those countries are the top three suppliers of solar panels to the U.S.

In the letter Tuesday, NextEra asked that the department either reject the applications or require the petitioners to re-file with the names of the members disclosed. An attorney for American Solar Manufacturers Against Chinese Circumvention and spokespeople for Commerce didn’t immediately address emails seeking comment.

The pushback comes amid escalating trade tensions between the U.S. and China over solar. Multiple companies have now had solar components detained at U.S. ports in the aftermath of a Biden administration ban on equipment using raw materials originally from Hoshine Silicon Industry Co., according to people familiar with the matter.

Making photovoltaic panels is a multi-step process that’s often done in separate factories, sometimes in different provinces or countries. Several Chinese companies, which dominate the market, have opened module-assembly plants in other nations in recent years. The American Solar Manufacturers Against Chinese Circumvention’s petitions argue that this creates an obvious route to circumvent U.S. tariffs against Chinese solar products.

The group said in its filings last week that identifying its members could lead to retribution against them. NextEra questioned the retribution claims and argued that company names don’t meet the standard for proprietary treatment.