Donald Trump's top counterterrorism official has resigned over the war in Iran, urging the president to "reverse course".

In a letter posted to X, National Counterterrorism Center Director Joe Kent said that Iran posed "no imminent threat" to the US and claimed the administration "started this war due to pressure from Israel and its powerful American lobby". 

The White House dismissed the letter, saying the president had "compelling evidence" that Iran was going to attack the US first. A US hate monitor accused Kent of "antisemitic tropes". 

With his departure, Kent is the most high-profile figure within the Trump administration to publicly criticise the US-Israeli attack on Iran.

In the Oval Office on Tuesday, Trump said Kent was a "nice guy", but "weak on security". 

He also said Kent's resignation letter had made him realise "it was a good thing that he's out".

In the letter addressed to Trump, Kent alleged that "high-ranking Israeli officials" and influential US journalists had sowed "misinformation" that led the president to undermine his "America First" platform.

"This echo chamber was used to deceive you into believing that Iran posed an imminent threat to the United States," the letter continued. "This was a lie."

Kent, a long-time supporter of Trump who unsuccessfully ran for Congress twice, was nominated by the president early in his administration and narrowly confirmed to his post. Democrats had criticised Kent's hiring of a member of the far-right Proud Boys as a consultant to his 2022 election bid. 

In his confirmation hearings, Kent also refused to back away from claims that federal agents had fomented the January 2021 riot at the US Capitol, or that Trump had not been defeated in the 2020 election. 

The Anti-Defamation League (ADL), a US antisemitism monitor, said in a statement that Kent's accusations "traffic in old-age antisemitic tropes". 

"So it's no surprise that he would blame Israel and the media for pushing the President into war against the Iranian regime," the ADL said. 

The pro-Israel lobbying group, the American Israel Public Affairs Committee (Aipac), reposted the ADL statement on X. Aipac did not immediately respond to a BBC request for comment.

Ilan Goldenberg, a senior official at the liberal pro-Israel advocacy group J Street, described Kent's letter as "ugly stuff that plays on the worst antisemitic tropes".

Kent, 45, is a US special forces and CIA veteran whose wife, navy cryptologic technician Shannon Kent, was killed in a suicide bombing in Syria in 2019. 

The father-of-two deployed 11 times overseas with the US military, including with the US Army's special forces in Iraq.

He later became a paramilitary officer at the CIA, before leaving government service following his wife's death. 

Kent cited his military service and his wife's death in his letter, saying 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". 

At the National Counterterrorism Center, Kent reported to Director of National Intelligence Tulsi Gabbard and oversaw the analysis and detection of potential terrorist threats from around the globe. 

Following Kent's resignation on Tuesday, Gabbard backed Trump's decision to go to war with Iran. 

In a statement posted on X, she said that as commander-in-chief, the president was responsible for determining what is and is not an imminent threat.

She noted that the Office of the Director of National Intelligence was responsible for helping to provide the president "with the best information available to inform his decisions".

"After carefully reviewing all the information before him, President Trump concluded that the terrorist Islamist regime in Iran posed an imminent threat and he took action based on that conclusion," Gabbard wrote on X. 

White House Press Secretary Karoline Leavitt said Kent's suggestion that "Trump made the decision based on the influence of others, even foreign countries, is both insulting and laughable". 

"As President Trump has clearly and explicitly stated, he had strong and compelling evidence that Iran was going to attack the United States first," she added. 

In a brief interview with the New York Times, conservative media commentator Tucker Carlson praised Kent, with whom he has close personal ties. 

"Joe is the bravest man I know, and he can't be dismissed as a nut," Carlson said. "He's leaving a job that gave him access to the highest-level relevant intelligence. The neocons will try to destroy him for that."

"He understands that and did it anyway," he added. 

There have been a number of resignations among senior officials in the Trump administration, including Securities and Exchange Commission enforcement director Margaret Ryan and Kennedy Center head Ric Grenell. 

President Trump's second term, however, has seen far less turnover than his previous tenure at the White House between 2017-21.