In his letter to Trump, former counterterrorism official Joe Kent said that he cannot support sending the next generation off to "fight and die in a war that serves no benefit to the American people nor justifies the cost of American lives."

WASHINGTON, March 19 (Xinhua) -- The Federal Bureau of Investigation (FBI) is investigating former counterterrorism official Joe Kent, who resigned in protest over the Iran war, for a possible intelligence leak, U.S. media reported Wednesday.

Kent, also the first senior member of Trump's administration to quit over the war, claimed that he "cannot in good conscience support the ongoing war in Iran."

In his letter to Trump, Kent said that he cannot support sending the next generation off to "fight and die in a war that serves no benefit to the American people nor justifies the cost of American lives."

On Tuesday, Trump dismissed Kent's claims, calling him "weak on security" and making clear that anyone in his administration who does not view Iran as a threat is not welcome.

The rebuke stood in stark contrast when Trump nominated Kent for the post last year, praising him as a man who had "hunted down terrorists and criminals his entire adult life."

Recent polls show that several key Make America Great Again opinion leaders have publicly voiced their opposition to the Iran war.

Kent's resignation deepened the division among Republicans regarding the war and the U.S. relationship with Israel.

Trump, who remains attuned to the right-wing media, criticized Kent following his departure, saying, "It's a good thing that he's out because he said Iran was not a threat."

Analysts say the resignation of a top U.S. counterterrorism official signals mounting pressure on the Trump administration over the Iran war, amid intensifying criticism from Democratic lawmakers, business leaders, and even segments of his own support base.

"Donald Trump created a mess in the Middle East, and he clearly has no plan for how to end it," Senate Minority Leader Chuck Schumer, a New York Democrat, wrote on X Monday.

Former Congresswoman Marjorie Taylor Greene, once a vocal Trump supporter who in recent months broke with the president and resigned from her post in January, said in a post on X after the war broke out that "War with Iran is AMERICA LAST and we voted against it."

Since the United States and Israel launched attacks on Iran on Feb. 28, at least 13 American service members have been killed. Ten others have been seriously wounded and about 200 injured, according to a report by The Wall Street Journal on Friday.