Timothy Stanley is a historian and columnist for Britain's Daily Telegraph. He is the author of "Citizen Hollywood: How the Collaboration Between LA and DC Revolutionized American Politics." The opinions expressed in this commentary are his.

(CNN) Having sacked Rex Tillerson as secretary of state, President Donald Trump has signaled that other heads could be meant for the guillotine. Perhaps as many as nine . Cabinet massacres of that scale are usually a sign of instability, even failing leadership. It wasn't Jimmy Carter's Crisis of Confidence speech in 1979 that destroyed his credibility so much as the mass Cabinet firing that followed it.

But Trump isn't Carter. Carter's problem was that he had lost sight of where he was going or what he wanted. Trump knows what he wants, but one of his biggest challenges is he lacks the personnel to get it done.

There are two good grounds for a Cabinet bloodbath. One, kick out the embarrassments. That includes Veterans Affairs Secretary David Shulkin, who was accused of misusing taxpayer money on a trip to Europe, or Housing and Urban Development Secretary Ben Carson, who apparently purchased (then canceled) a dining set that cost $31,000 for his work office. Conservatives should know better. The public wants to see its politicians eat off paper plates.

Second, kick out the people who undermine the boss. It's one thing to have a Cabinet that reflects a diversity of opinion, such as Lincoln's famous team of rivals. But when the President has a clear agenda that requires a radical departure from the status quo, he cannot have officials contradict it. Tillerson went, we speculate, because he wanted to save the Iran nuclear deal and have a friendlier relationship with China.

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And H.R. McMaster, the national security adviser, might well go for similar reasons. If this happens, Trump would not only be right to fire someone who disagrees with him but he'd also be doing it for the right reasons, although he should tread carefully when it comes to a replacement.

Reportedly under consideration is former UN Ambassador (under George W. Bush) John Bolton, a perennial hawk whose appointment might be seen as a repudiation of Trump's anti-Iraq War, relatively anti-interventionist stance. It would be, say some, a betrayal of the President's base.

But Bolton deserves credit for at least one thing: opposing the foolish Iran nuclear deal. It's the classic product of State Department and European diplomatic thinking, rooted in a basic misunderstanding about how dictatorships work. They are not, as the establishment appears to think, regimes of gentlemen who honor their word: Iran is already unveiling l ong-range missiles at the same time it is locking up British citizens in contravention of their human rights.

Nor are dictatorships going to be around forever. They live under the constant threat of revolt, as the recent protests in Iran show. Dynamic American leadership could contain the mullahs or even encourage the forces that will edge them from office. Trump is right to disregard European opinion and act tough on Iran.

The same goes for China. I will go to my grave never understanding the West's paradoxical approach to Moscow and Beijing: Russia has been treated, reflexively, as a pariah state, which it undoubtedly shows signs of becoming. Meanwhile the West bestows mounting economic power on China as if it were its favorite child.

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Time to grow up. China, like Iran, is a disingenuous dictatorship that maintains power by a mix of bribery and force; President Xi Jinping has just rewritten the rules so he can govern for life. The Middle Kingdom is every bit as much a strategic threat as Russia, if not more so. Trump's action on steel and aluminum is a belated attempt to correct the power balance between East and West, and the prize isn't just about protection of US industry, but also about forcing China to observe international rules and play a more constructive role in the Korean Peninsula.

Stability in the Koreas would mean America could finally ease away from the region, just as a defanged Iran permits further withdrawal from the Middle East. Trumpism is an attempt to square short-term engagement with long-term disengagement, with the eventual goal of making America a little less responsible for all the world's problems.

This is revolutionary stuff. Diplomats don't do revolutionary thinking because they are emperors of their own precious bureaucracies. Hence, Trump needs an administration that is willing to push the State Department in directions it doesn't want to go.

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Of course, Cabinet members cannot take total responsibility for how an administration performs, and Trump routinely undermines even his best advisers. From Europe, the line on Russia appears frustratingly unclear, even naïve, at a time when Moscow is accused of perpetrating a nerve agent attack on British soil (Trump, thankfully, has said that if the British insist they have the evidence for it, he's willing to believe their theory).

For all the flaws of Trump the man, Trumpism needs a coherent application in foreign affairs if it is to have a shot at effecting change. The Pennsylvania result shows that by next year, Trump could be dealing with a Democratic House, even Congress. If he believes that a fresh Cabinet is necessary to turn things around, clearing out the staff, though alarming, is not illogical.

His window of opportunity for change is starting to close, and he should act before he becomes Nancy Pelosi's prisoner. And, no, Mr. President, you won't be able to sack her, too.