A column co-authored by former U.S. Defense Secretary Jim Mattis which called for an end to President Trump’s “America First” foreign policy did not include a disclosure regarding the retired four-star general’s work with the Cohen Group, an international business advisory firm active in China.

Mattis was one of four listed authors for the column published by Foreign Affairs and entitled “Defense in Depth: Why U.S. Security Depends on Alliances—Now More Than Ever.” The column said the United States’ “principal external threat” was an “aggressive and revisionist China—the only challenger that could potentially undermine the American way of life” and called for a shift toward increased international cooperation to counteract China’s influence.

The column disclosed Mattis’ roles as a fellow at the Hoover Institution and the former Secretary of Defense, but did not reference his work with the Cohen Group, where he has served as a “senior counselor” since September 2019. The firm, which advises clients on international business deals, has two offices located in China.

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Cohen Group representatives could not immediately be reached for further comment. The Washington Times was first to note the lack of a disclosure.

China is one of several international markets in which the Cohen Group is active. On its website, the Cohen Group describes China as a “market of enormous opportunity and complexity.”

“TCG enables Fortune 500 Companies, as well as small- and medium-sized enterprises, to achieve their commercial goals in China through tailored government, business, and media relations strategies,” the website says.

Trump took a hardline stance on China upon entering the White House in 2016. The president enacted a series of tariffs on Chinese-made goods, prompting a lengthy trade war, and has repeatedly ripped Beijing over its handling of the coronavirus pandemic.

Mattis’ column asserts that America should “maintain robust alliances in Asia,” return to a leadership role in international organizations and seek to diversity global supply chains to reduce reliance on Chinese-made goods.

“Crucially, the United States should not press countries to choose outright between the two powers,” the column said. “A “with us or against us” approach plays to China’s advantage, because the economic prosperity of U.S. allies and partners hinges on strong trade and investment relationships with Beijing.”

The authors called on President-elect Joe Biden’s administration to “quickly revise the national security strategy to eliminate “America first” from its contents, restoring in its place the commitment to cooperative security that has served the United States so well for decades.”

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Mattis served as secretary of defense from 2017 to 2019. Since leaving the Trump administration, he has been critical of the president’s leadership.

Trump lashed out at Mattis following the column’s publication, tweeting that he “should have fired him sooner” and referring to him as the “world’s most overrated general.”

Secretary of State Mike Pompeo also pushed back on Mattis’ remarks during an appearance on Fox News Channel earlier this week.

"I have a lot of respect for Jim, but he's just dead wrong on that," Pompeo told "Special Report" host Bret Baier. "'America First' has been at its heart, a recognition that when America is secure at home, when America does good things for our own economy, for our own prosperity, that America will be a force for good.”