Iran-allied Pakistani national charged over plot to assassinate Donald Trump

Asif Merchant, 46, reportedly travelled to New York and was working with assassins to kill the 45th President in late August or early September.

Charges filed by federal prosecutors in Brooklyn revealed Merchant was arrested on July 12, just hours before a lone gunman opened fire at a Trump rally in Pennsylvania.

Merchant came unstuck after meeting with purported hitmen who actually ended up being undercover law enforcement officers.

The 46-year-old, who is not seemingly connected with last month's assassination attempt in Butler, remains in federal custody.

Merchant allegedly arranged to pay the supposed assassin a $5,000 advance on the assassination.

He was reportedly planning to leave the country before the assassination but was arrested before he could go.

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"For years, the Justice Department has been working aggressively to counter Iran's brazen and unrelenting efforts to retaliate against American public officials for the killing of Iranian General Soleimani," Attorney General Merrick Garland said in a statement.

"The Justice Department will spare no resource to disrupt and hold accountable those who would seek to carry out Iran's lethal plotting against American citizens, and will not tolerate attempts by an authoritarian regime to target American public officials and endanger America's national security."

Thomas Matthew Crooks' shooting at Trump's rally in Butler last month resulted in one supporter being killed, with a further two injured.

Trump was snapped holding his arm aloft as blood streaked across his face from his ear.

The Secret Service came under fire for its handling of the situation, with chief Kimberly Cheatle eventually opting to resign as the agency's director.

Despite no connection between Crooks and Merchant, the Secret Service might have made some last-minute adjustments following the 46-year-old's arrest.

"We were initially told that there was no Secret Service snipers coming but that was shifted either Thursday or Friday to indicate that there were," Pat Young, head of the Beaver County Emergency Services Unit, told ABC News.

"We had been told that this is the first time that a non-sitting president had been allocated Secret Service snipers. So that threw up some alarm bells for some of our guys that -- why the sudden shift -- from one stance to the other?"