One of the men hasn't been arrested and is believed to be in Iran.

Prosecutors say the plan dates back to September before the presidential election.

Our North America editor Sarah Smith is in Florida tonight.

Sarah.

Yeah, the three men have been charged with trying to assassinate Donald Trump during the presidential campaign and doing so under the instruction of the Iranian Revolutionary Guard.

The criminal complaint alleges that an Iranian asset was told to hire people in the United States to conduct surveillance on Donald Trump and ultimately to try to assassinate him.

They were told that money was no object whatsoever.

But if they couldn't get the plan together within seven days, then they were to wait until Donald Trump loses the election, they were told, when the would be easier to kill him.

Enjoying his victory on Tuesday night, Donald Trump could also celebrate surviving the campaign after two serious attempts to kill him and a separate Iranian assassination plot.

As you know, there have been two assassination attempts on my life that we know of, and they may or may not involve, but possibly do, Iran.

President Biden said it would constitute an act of war if Iran tried to kill Donald Trump after US intelligence services warned of a specific Iranian plot.

We've been threatened very directly by Iran.

And I think you have to let them know because the best way to do it is through the office of the president that you do any attacks on former presidents or candidates for president, your country gets blown to smithereens, as we say.

Donald Trump narrowly survived being killed at a rally in Butler, Pennsylvania, when a bullet grazed his ear.

The gunman was killed at the scene, and his motives remain unknown.

Another would be assassin was arrested when he was discovered with semi-automatic rifle hiding in the bushes when Donald Trump was playing golf.

He was angry about the war in Ukraine.

Top Iranian general Qasem Soleimani was killed in a US drone strike in Iraq at the end of Donald Trump's first term as president.

He considers that a very proud achievement.

Soleimani has been perpetrating acts of terror to destabilise the Middle East for the last 20 years.

What the United States did yesterday should have been done long ago.

The Iranian regime insists Donald Trump should face trial for what the United Nations declared to be an unlawful killing of General Soleimani, and has said that if he's not tried in court, then Iran will take its revenge.

President-elect Trump will surely now be considering his response to Iran.

Sarah Smith, BBC News, West Palm Beach.

Well, we'll have more from Sarah in a moment, but first, though, let's talk about the implications of all of this with our correspondent, James Landale, and how will this affect policy potentially once Donald Trump is actually in office?

Well, Jane, as Sarah made clear in her report, Donald Trump and Iran have history.

Not only did he order the assassination of that Iranian Revolutionary Guard General Qasem Soleimani, he also imposed a policy of what he called maximum pressure on Iran, effectively stiff economic sanctions designed to make it much harder for Iran to fund its proxy militias, Hamas and Hezbollah.

He also pulled Iran, the United States, out of an international deal that was designed to curb Iran's nuclear ambitions in the return for lifting those economic sanctions.

But that was four years ago.

The world is very different now.

Iran is locked in a direct war with Israel, and Israel's Prime Minister, Benjamin Netanyahu, wants to step up his attacks on Iran, potentially even targeting its nuclear and energy facilities.

Now, thus far, Joe Biden has resisted this, fearing escalation.

The question now is, will Donald Trump say, actually, no, we want to give Israel a freer hand?

Some of his aides say that is possible because he will take this kind of plot personally.

Others, they disagree.

And they say, look, remember, Donald Trump said, and I quote in his victory speech, I'm not going to start wars, I'm going to stop wars.

So it may be that he wants not to escalate a conflict that potentially could the United States in.

So Iran could be the first big test of the Trump presidency, a test between his heart saying revenge, his head saying caution.

I think what is clear, though, is the moment he takes power, that we will see maximum pressure marked to a big package of sanctions against Iran designed to stop basically selling oil to China.