In the parade of prospective cabinet picks making their way to the penthouse of Trump Tower to meet with the president-elect, few have come with more pedigree or more (figurative) baggage than General David Petraeus. Tipped for the position of secretary of state, the retired four-star general is considered to bring with him a wealth of experience garnered from nearly 15 years in the higher echelons of the U.S. Army, including time spent at the helm of operations in Iraq and Afghanistan as well as a stint as head of the CIA. But in his interview to become the nation's top diplomat, he likely had some awkward questions to answer regarding a scandal involving the sharing of state secrets with his biographer and paramour, Paula Broadwell. At least he should have. But Donald Trump has been vocal in his defense of the general even though he was found guilty of the same crime committed by Hillary Clinton. Perhaps a more likely sticking point between Trump and Petraeus, however, will be their diverging views over the USA’s commitment to NATO and its continued expansion.

Granted, David Petraeus shot to prominence due to the successful counterinsurgency methods he employed as the commander of forces in Iraq that resulted in a substantial drop in violence. As the head of the Command and General Staff College at Fort Leavenworth two years prior to that, Petraeus wrote the military’s manual on counterinsurgency strategy. After taking charge of the forces in 2007 he brought Sunni fighters onto the U.S. payroll, reasoning that these local groups were better placed to pacify their communities than foreign forces could ever be. Moving troops out of their heavily fortified bases and into smaller, exposed checkpoints throughout the country helped the U.S. regain some of the respect it had lost amongst Iraqis.

After serving as head of Central Command, Petraeus became the Director of the CIA, where he met his downfall after revelations of an affair with his biographer. While the affair in itself might not have cost him his job, the fact that he shared top secret documents with Mrs. Broadwell, certainly did. In 2012, Petraeus pleaded guilty to felony charges after an investigation found that he had given Mrs. Broadwell eight “black books” with highly classified information including “the identities of covert officers, war strategy, intelligence capabilities and mechanisms [and] diplomatic discussions”. Sentenced to two years probation and a fine of $100,000, many thought he got off lightly for a crime that a more lowly officer would likely have faced a much stiffer penalty.

It's no wonder then that the mention of Petraeus as possible secretary of state has raised hackles from Democrats. The investigation into Clinton’s own mishandling of sensitive emails never went so far as to accuse her of purposely sharing state secrets, like Petraeus did, but merely of being reckless in securing them. Moreover, Petraeus was found guilty of attempting to subvert the course of justice by hiding the books in question from investigators.

Clearly, Donald Trump sees none of this as a problem. Where the two men might fall out, however, is over the U.S. role in NATO and its ever-deeper expansion into Russia's backyard. Whereas Donald Trump has called into question the U.S.'s obligation to come to the aid of another member state under attack, Petraeus does not seem to share the President-elect’s spirit on that matter and is adamant that the U.S. will keep to its commitments. But given that corruption is endemic in many NATO members especially in Eastern Europe, Trump is justified in rethinking America’s defense commitments. The first test is likely to come ahead over the proposed NATO enlargement to include Montenegro after the tiny Balkan state was invited to join last year. How much Donald Trump knows about Montenegro is anyone’s guess but if he has been following recent events in the country he will have observed little to convince him that it's the kind of place that the U.S. should be rushing to protect in case it is attacked.

In October, Montenegro's Prime Minister Milo Djukanovic stepped down after his party lost the majority in Parliament and was replaced by close ally Dusko Markovic. This comes after a 25-year reign of power for Djukanovic during which time he faced accusations of cigarette smuggling, bank fraud, and embezzlement, while critics charged that he turned the former Yugoslav state into a hub for international crime gangs. In 2009, Djukanovic admitted to his role in a $1 billion cigarette smuggling operation involving the Italian mafia and only walked free after invoking diplomatic immunity. This is merely the abridged version of Djukanovic’s rap sheet, and no one is under any illusion that he will remain a major figure behind the scenes, as he has on past occasions strategically stepped away from power to pull the strings in the background.

If this is the caliber of a partner that the U.S. can expect in its NATO allies, then Donald Trump is justified in his misgivings. However, whether or not Trump appoints Petraeus -- a no-questions-asked supporter of the current NATO alliance -- is a major test of his credibility before the electorate as well. Worse, appointing Petraeus risks marking Trump a hypocrite regarding the Clinton email affair, which will not sit well with those who have voted him into office.