During a speech on security policy in September, Trump promised his dealings with the world would be based on "diplomacy, not destruction". But many of his sometimes contradictory statements on foreign policy have suggested the opposite, leaving defence experts scrambling after his surprise election victory over Hillary Clinton to evaluate how Trump would shape the United States' military posture.
Brian Katulis, a senior fellow at the Center for American Progress, a left-leaning think tank, said that Trump and Vice-President-elect Mike Pence had expressed a range of positions "but never offered a full blueprint" on security issues. "America is in uncharted territory on defence policy," he said.
Some of the statements that have created the most consternation among current and former officials included suggestions that the United States could withdraw from Nato, statements of support for allowing new nuclear nations, and a proposal to "take out" families of suspected terrorists. He also said that he would resume imprisonment of terrorist suspects at Guantanamo Bay, which President Obama has struggled for eight years to close, and renew the use of torture during prisoner interrogations.
As a candidate, Trump has suggested in some cases a more muscular response to events overseas, possibly including to China's land reclamation activities in the South China Sea. The candidate also promised a harder line on Isis but has provided little detail about how he would do so.
Trump could take office with two major US-backed offensives underway in the Syrian city of Raqqa and the Iraqi city of Mosul, providing allied forces an opportunity to deliver a major blow against Isis militants and offering the next president a chance to claim a tactical victory.
In other areas, Trump has suggested a more conciliatory approach to US adversaries. Those include Russian President Vladimir Putin, despite his annexation of Crimea in Ukraine, and Syrian President Bashar al-Assad, despite the country's spiraling civilian death toll. Trump also signalled less appetite for foreign interventions than his competitor might have favored.
Trump supporters have suggested the President-elect won't deliver on his most inflammatory statements and say that they expect continuity on many central defence issues: commitments to defend Nato members, alliances with South Korea and Japan, even something close to the uneasy status quo with Russia.
Some of Trump's proposals may encounter resistance from military leaders, including a suggestion that he would broaden military cooperation with Russia in Syria. A similar Obama Administration proposal earlier this year generated intense Pentagon opposition, as military officials worried about giving Russia valuable insight into their operations.
Other proposals from Trump will sit well with the military leadership. He has promised to eliminate congressionally mandated spending caps, for example, and restore cuts to personnel and equipment that he said have left the military dangerously unprepared. If he can succeed in getting Nato nations to contribute more to shared defence without rupturing the alliance, it would also be a popular move.
O'Hanlon said Trump "could find a way to find a kinder, gentler way to pressure the allies to burden share, and he need not withdraw commitments or he need not do it immediately".
No matter what, Trump may find it harder to execute his defence plans once in office than expected.
"I think he will discover what Mitt Romney would have discovered in 2012, which is that the money has to come from somewhere" to pay for defence priorities, said Christopher Preble, a scholar at the libertarian Cato Institute. While Trump has promised to pay for military spending increases with government savings, a major boost could run afoul of Congress if it required new borrowing or a tax increase.
The defence bureaucracy could prove difficult to tame in other ways if, as has taken place in the past, Pentagon leaders push back against the White House during the policymaking process or publicise information that can sway public opinion about pressing defence issues.
Uniformed leaders, in keeping with the law and military tradition, are certain to fall in line with presidential mandates. The exception would be if those orders break the law, as his proposals to permit torture or intentionally attack civilians would probably do.
The sheer volume of defence issues facing the next president means that President Trump will need to delegate to his staff.
While Trump has distanced himself from the traditional Republican foreign policy establishment, some veterans of the George W. Bush administration are expected to flock to government again. Several Republican leaders, including Senator Jeff Sessions have been named as a potential Defence Secretary pick.
