(NewsNation) — Former Secretary of State Mike Pompeo continues to receive 24-hour security following what the State Department says is a credible threat against him, costing taxpayers an unprecedented amount of money.

His security price tag is higher than protection costs for some former presidents. A NewsNation investigation found that it isn’t necessarily the threat against Pompeo that’s costing taxpayers, however. Pompeo also keeps a busy schedule of non-essential travel, including trips that his own security has warned him not to take.

The former secretary of state’s travel schedule is packed. No longer serving as the nation’s top diplomat, Pompeo continues to be heavily guarded. That’s in part because he still faces a credible threat from Iran, in connection to his role in the assassination of Iranian General Qasem Soleimani in 2020.

In a speech this year, Iran’s president said martyrs would “take revenge” on Pompeo.

Sources around Pompeo, however, told NewsNation that he’s ignoring the advice of his security and ultimately costing taxpayers.

NewsNation obtained sensitive but unclassified documents that show the cost of protecting Pompeo and one of his aides ballooned in 2021 from nearly $700,000 to more than $2 million each month. About 90% of those public dollars go to Pompeo’s security.

That $2 million mostly covers “vehicle and travel costs for Pompeo’s security agents and his own extensive travel for paid speeches and public events,” according to the documents obtained by NewsNation.

It’s not uncommon for former officials to go on book tours or travel for paid speeches, retired Diplomatic Service Agent Mark Hipp said. But when there’s a credible threat, announcing when and where you’ll be somewhere puts lives at risk, he added.

“There’s a stark difference between a national security mission that’s important for us and then a discretionary trip,” Hipp said. “In all things, especially if there’s a threat from a state sponsor, you’d have to be concerned.”

That’s particularly true when the trip is for personal gain, Hipp said.

Pompeo nets about six figures per speech.

“Most secretaries if not all pretty much do this stuff,” Hipp said. “It’s to what extreme they do it.”

Below is a look at just some of Pompeo’s domestic travels from April to July of 2022. Many of the appearances were announced ahead of time, a factor that Hipp said makes security’s job more complicated.

Congressman Brad Sherman serves on the House Foreign Affairs Committee and says when it comes to personal travel, finding a balance between what the public has to pay and legitimate security concerns is tough.

“I’m very reluctant to say if you go into public service and you do things that may get you shot by a foreign adversary, then you can’t go on a book tour,” Sherman said. “But the amounts of money that you’re talking about — millions a month — damn!”

NewsNation learned that before this year, Congress limited how much it spent on security for former state department officials to $15 million annually. After Pompeo’s detail nearly doubled that amount, Congress rewrote its budget, this year providing as much as $30 million.

“I want the professionals to decide: How big is this security detail and does Pompeo need security, and if so, where?” Sherman said.

The professionals did decide that a planned trip in November to the United Arab Emirates was too risky for Pompeo and his agents, in light of the threat against him.

Pompeo’s security warned him not to go, but he dismissed the state department’s concern and went anyway, sources told NewsNation.

The paid gig earned Pompeo hundreds of thousands of dollars. It also took place as many security officials and diplomats acknowledged the UAE was a target of Iran. Pompeo was one of those diplomats and acknowledged in a January interview two months after his visit that a missile attack in the UAE was conducted by Iran.

The incident didn’t deter other overseas trips to destinations including Israel, South Korea, Switzerland and London.

That’s in addition to what sources exclusively told NewsNation is a planned $1.1 million taxpayer-funded upgrade to Pompeo’s new $3.5 million Virginia home — to amp up security.

Pompeo did not answer NewsNation’s questions, and multiple requests for interviews went unanswered.

A statement from the U.S. State Department read in part:

“The Bureau of Diplomatic Security (DS) works with Department leadership and Congress to ensure that we have adequate personnel and resources to carry out protective operations and our global security mission.  As new requirements arise and threats evolve, we will seek the necessary resources to ensure mission success.”

NewsNation Digital Reporter Katie Smith contributed to this report.