U.S. Sen. Lisa Murkowski, R-Alaska, today sent a letter to Secretary of Commerce Penny Pritzker asking whether any oil exchanges with Mexico have actually been approved, months after the Administration announced in August it would allow such transactions.

Murkowski, chairman of the Senate Energy and Natural Resources Committee, proposed “swaps” or exchanges of American light oil for Mexican heavy oil in 2014. This past February, she led a bipartisan letter calling for both the approval of cross-border transactions and a national interest finding from the Administration authorizing all crude oil exports to Mexico on the same basis as they are already permitted to Canada.

The press reported in August that the Commerce Department was approving oil exchanges with Mexico, as is fully permissible under existing law, and the department itself stated that it was “acting favorably” on multiple applications.

In the letter Murkowski sent today, Murkowski questions whether licenses were ever issued: “I am troubled though by conflicting information that has emerged in recent weeks concerning these oil exchanges. Despite great fanfare in the press, there are indications that no such transactions may have actually been approved. I would greatly appreciate clarification on this issue.”

The full letter is available on the committee’s website.