A desire to evade President Barack Obama's long shadow seems to be at the center of any number of momentous foreign policy decisions President Donald Trump has made. In abandoning the Trans-Pacific Partnership, the Paris climate agreement and the rapprochement with Cuba, among other moves, Trump sought to cast aside his predecessor's marquee achievements. And, of course, Trump would love nothing more than to defeat Obama's vice president, Joe Biden, at the ballot box; his treacherous efforts to do so by enlisting the help of the government of Ukraine are at the heart of his pending impeachment trial in the Senate.

However, a president who largely predicates his foreign policy not on the national interest but on a more shortsighted, personal and dangerous inclination — the desire to "best" his predecessor — was always going to carry significant risks for the country.

Nowhere are the dangers of that tendency more obvious than in the crisis between Washington and Tehran. That's because virtually all of the provocations of recent months — Iran's and its proxies' attacks against our military assets and installations, its ballistic missile strikes against our partners and the violence directed at our embassy in Baghdad — stem from Trump's decision in May 2018 to abandon the Iran deal.

The ensuing "maximum pressure" campaign by the Trump administration, which reimposed sanctions on Tehran, sparked the provocations and attacks that have so far culminated in the Trump administration’s targeted killing of Gen. Qassem Soleimani, commander of Iran's Quds Force, and Tehran’s barrage of ballistic missile strikes on Tuesday night U.S. time, targeting Iraqi military bases housing U.S. troops. Both have pushed us even closer to the brink of open conflict.

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By leaving the deal, however, Trump took aim more at his predecessor than he did at the specific contours of the agreement, with which Trump almost certainly wasn't familiar. In fact, when President-elect Trump met with Obama in the Oval Office in November 2016, Trump — according to a readout of the meeting I received — expressed surprise when he heard how the deal verifiably prevented Iran from obtaining a nuclear weapon. He even asked Obama why his administration hadn't made those compelling details public. (Take it from me: We had. Republicans hard-liners hardly wanted to listen.)

As president, however, Trump quickly resumed his broadsides against Obama — going so far as to claim that Obama had wiretapped Trump Tower — and the Iran deal became collateral damage. In interviews and especially at rallies with his political base, Trump routinely personalized the deal, calling it the "Obama deal," and, on dozens of occasions, invoking Obama's name to rail against the pact, which he termed the "worst deal ever." In Trump's rhetoric — and presumably in his mind — the Iran deal became inextricably linked with Obama.

That may explain why Trump opted to abandon the deal over the advice of his national security team and despite the intelligence community's private and public assurances that it was working.

Before the latest cycle of violence, moreover, Trump was reported to have come to accept that any "better deal" would have to closely resemble Obama's in everything but name — underscoring that the decision to leave it was less about Iran and more about Obama. That wasn't lost on our British partners, whose former ambassador to Washington informed London in communications that were supposed to be confidential that the decision was an act of "diplomatic vandalism" to spite Obama.

Much the same could be said of Trump's approach to North Korea, which he has pursued chiefly for political advantage rather than for the national interest. The president seems to have calculated that an easing of tensions and even cosmetic concessions from Kim Jong Un could be packaged as a foreign policy win, which he desperately needs. But just as important for Trump is that his approach allows him to trumpet engagement with the North Korean leadership that is unprecedented for any other president — but especially Obama.

Trump hasn't minced words. Late last year, for example, he claimed that, during their pre-inauguration Oval Office sit-down, Obama confided that he didn't know how to solve the North Korean challenge. Doubling down on the lie, Trump added that Obama had supposedly tried to reach out to Kim 11 times but had been unsuccessful. He added: "But the man on the other side — the gentleman on the side — didn't take his call. OK? Lack of respect." What's more, Trump has repeatedly bragged about his relationship with Kim, noting that it's unique to his presidency. As he told Sean Hannity last summer: "We have a relationship. President Obama had no relationship."

The results of emphasizing splashy, camera-friendly summitry to showcase that relationship over dogged diplomacy have been predictable. While Kim's concessions were always flimsy and reversible — as we've seen in recent weeks — they were just enough to give Trump the political grist he sought. In return, Trump has offered Kim a long leash.

Indeed, Pyongyang's missile and rocket tests and its heightened tenor of saber-rattling, including Kim's New Year's Day threat to demonstrate a new "strategic weapon," have been condemned by the international community and even by some of Trump's most senior advisers but not by Trump himself. Pyongyang appears to recognize that Trump isn't willing to squander the personal relationship that — for better or for worse — sets him apart from Obama.

Trump, by placing his personal interests and grievances above national security, has made many grave strategic errors — but also now a tactical one in Iran, with profound implications for his political prospects. He failed to realize that the once-hidden costs of his moves could come to the fore at the outset of 2020. He enters the election year facing unprecedented tests on the world stage and at home for which he and his team (fully three years into his term) seem woefully unprepared.

Ultimately, his gambits to best Obama may ensure that Trump will be something his predecessor wasn't: a one-term president.