President Trump has been one of the most rhetorically bellicose commanders in chief in modern American history. He’s bragged about the size of his “nuclear button,” repeatedly threatened military action and used playground taunts to demean America’s adversaries.

But in the first 15 months of his presidency, Trump has been cautious when it comes to actually using military power and putting U.S. forces in harm’s way.

The last two weeks could mark a major turning point in his presidency. In selecting John Bolton as his new national security adviser and Mike Pompeo as his secretary of state, Trump has elevated two of the most consistently hawkish Republicans in Washington.

Now, the question is how these two Trump advisers will change a president with few, if any, fixed views on foreign policy.

Bolton, a Fox News commentator and prolific writer, brings a coherent and unusually controversial foreign policy philosophy to the White House. He has been a fervent advocate for using American military power to prevent rogue regimes, such as Iran and North Korea, from acquiring and proliferating nuclear, biological and chemical weapons.

“He is unabashed about this,” said Mark Groombridge, a former top adviser to Bolton at the State Department and United Nations. “He has no problems with the doctrine of preemption and feels the greatest threat that the United States faces is the proliferation of weapons of mass destruction.”

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Pompeo has described Iran as “a thuggish police state” and a “despotic theocracy.” Both men have described the landmark Iran nuclear deal as “disastrous.”

Trump was initially drawn to Lt. Gen. H.R. McMaster, who he dismissed Thursday as national security adviser, for his reputation as a warrior in Iraq and Afghanistan. But McMaster’s methodical and academic style grated on the president, who often complained that he couldn’t stand being around him.

Bolton and Pompeo are much more of a stylistic match. “Trump likes the pugnacious, tough-guy style, and they reinforce it,” said Eliot Cohen, a former Bush administration official and Trump critic.

They are also far more savvy bureaucratic operators than McMaster, who had never served in Washington and often tried to wear Trump down rather than woo him.

The challenge for Bolton and Pompeo will be convincing Trump to support their aggressive plans.

McMaster pressed the Pentagon for military options to strike targets in Iran. But his entreaties were routinely rebuffed by Defense Secretary Jim Mattis, said U.S. officials.

“Mattis has been daggers drawn with H.R. on everything,” said a person close to both men.

In most of these disputes Trump either backed Mattis or did not weigh in with his feuding advisers.

[Trump’s favorite general: Can Mattis check an impulsive president and still retain his trust?]

In Afghanistan, McMaster took a similarly tough line, pressing Trump to agree, against his own instincts, to double the size of U.S. forces to 15,000 troops and back a strategy that relies heavily on America’s ability to improve Afghanistan’s inefficient and corrupt government. But Trump never seemed to buy into the new strategy and resented McMaster for pushing it on him, U.S. officials said. Pentagon officials have said that they feel under intense pressure to show progress on the battlefield this year before Trump pulls the plug.

Neither Bolton nor Pompeo share McMaster’s belief that U.S. power can or should be used to reshape the world or spread democracy. “Bolton is almost entirely focused on U.S. national security,” said David Bosco, an international relations professor at Indiana University who has interviewed Bolton for his work. “He has very little patience for the idea that the U.S. should be spending blood and treasure to improve other countries.”

In that way, both Bolton and Pompeo are much more of an ideological match with Trump. Their biggest impact in the immediate term could be on Trump’s planned summit with North Korean leader Kim Jong Un, scheduled to take place by the end of May.

In approaching North Korea, Bolton has suggested that Trump should demand that the Kim Jong Un denuclearize and allow international arms inspectors unfettered access to the country — an outcome most Korea experts say is highly unlikely.

Absent a total North Korean capitulation, Bolton is likely to press Trump to reject lesser concessions such as a freeze of North Korea’s nuclear program, said those who have worked with him.

“John hates the word ‘freeze,’ ” Groombridge said. “Hates it.”

Bolton and Pompeo also share Trump’s intense frustration with the nuclear agreement that the United States and five other world powers reached with Tehran during the Obama administration. They will play key roles in advising Trump next month on whether to amend it or drop it entirely.

Bolton and Pompeo will likely make their biggest impact on the daily operations of the Trump administration. For much of the last six months, if not longer, McMaster and Secretary of State Rex Tillerson were widely viewed as weak and wounded players inside the administration.

As CIA director, Pompeo has spent more time at the White House than previous directors, cultivating a relationship with Trump. He’s likely to try to forge deeper ties at the State Department than Tillerson, who often ignored the diplomatic corps.

“Pompeo has shown that he’s committed to working with the team that’s given to him,” said Danielle Pletka, a senior vice president at the American Enterprise Institute. “At State, he’ll hear very different things than what the president wants him to hear.”

At the White House, Bolton is likely to reinforce Trump’s “America First” view of the world. Both the president and his new top adviser share a long-standing animus to any treaties, international laws or alliances that limit America’s freedom to act on the world stage.

Bolton has also shown that he knows how to influence Trump. Even when he was frozen out of a White House job at the start of the administration, Bolton managed to gain access to the president.

For a brief period after White House Chief of Staff John F. Kelly took over, Bolton was even completely blocked from the Oval Office. But the ban didn’t last for long. Bolton won back his contact by drafting a plan to help Trump get out of the Iran deal at the same time that the president’s advisers were encouraging him to stay in it.

As national security adviser, Bolton’s former colleagues said he would make access to Trump his top priority. His model: Henry Kissinger.

“John always said that he admired Kissinger,” Groombridge recalled. “His model is very much an imperial-style National Security Council.”