He vowed to "obliterate" Islamic State if he became President of the United States.
Now Donald Trump appears to be following through on that promise after announcing military plans to "extinguish" the terror group once and for all.
As talk grows of coalition forces reclaiming Islamic State's de facto capital Raqqa by the end of the year, and with US marines already deployed on the ground in Syria, Trump's promise looks achievable.
But how successful will he be and can the terror group ever really be defeated?
According to Dr Rodger Shanahan, a research fellow at the Lowy Institute, the question of whether Trump can defeat IS depends on "what you mean by defeat".
"If the definition of defeat means to take back control of cities controlled by IS, then yes, that will be successful," Dr Shanahan said.
But Dr Shanahan warned while the terror group may lose control of strategic territory, it was unlikely to mean IS would ever truly be "obliterated".
He said Trump is a politician and could claim the regaining of IS-held territory as something which occurred under his watch as Commander-in-Chief.
"If he's a smart politician he will say it's his decisive action which decided that outcome," he said.
However Dr Shanahan said the fight against IS wouldn't end there.
He warned the foreign fighters who are left could return home, while homegrown fighters with vital support networks would be left to regroup, go underground, or join forces with other militant or jihadi forces.
He also said the US has played an active supporting role for some time in the fight against IS under the Obama administration, but noted the expanded role the country would now have on the ground in Syria.
The US announced yesterday that 200 extra troops would be deployed into northern Syria, widening America's footprint in the long and drawn out war to defeat the terror group.
"The marines are mainly providing artillery in support of the offence in Raqqa," Dr Shanahan said.
"We're not talking about a large role."
Dr Shanahan said the battle against IS was a complex one, especially in Syria, with the Kurds and Assad regime also playing different roles.
He said by partnering with the Kurds in the Raqqa assault, the US also risked being seen as entering into an indirect alliance with Russia, as well as the Syrian government, which it backs.
Trump has been strongly critical of the Obama administration's approach to defeating the terror group and said he would lead the fight to finally destroy IS.
Just this month, Trump announced military plans to "extinguish" the terror group.
"As promised, I've directed the Department of Defense to develop a plan to demolish and destroy ISIS - a network of lawless savages that have slaughtered Muslims and Christians and men, women and children of all faiths and all beliefs," he said.
"We will work with our allies, including our allies in the Muslim world, to extinguish this vile enemy from our planet."
The promise follows a memorandum he signed last month which directed his administration to "develop a comprehensive plan to defeat ISIS".
Pentagon leaders sent a new plan to defeat the militant group to the White House late last month.
It outlined a strategy that would likely increase the number of US troops in Syria in order to better advise and enable the US-backed Syrian fighters.
FIGHT STEPS UP
The United States is shifting from working quietly behind the scenes in Syria's conflict, turning instead toward overt displays of force in an attempt to shape the fight.
It means drawing troops into a long and costly war with unpredictable outcomes, but that's not Trump's only concern.
The deployment of 200 Marines also risks antagonising US-NATO ally Turkey. The Syrian Democratic Forces are led by the Kurdish PYD party, which Turkey says is a terrorist organisation.
The Marines' deployment, intended to back local forces in the campaign against the Islamic State group, came just days after another intervention.
Dozens of Army troops, riding Stryker armoured vehicles waving American flags, drove outside the Syrian town of Manbij in a mission aimed at keeping US allies Turkey and Syrian Kurds from fighting each other and focused instead on the fight against IS.
The latest dispatch brings the number of US troops on the ground in Syria to more than 700.
The previous troops were quietly sent by the Obama administration to work with local allies against IS; most of them were special forces and advisers, and none brought heavy weapons with them.
After months of preparations, US-backed Syrian forces are getting closer to launching an all-out assault on the Islamic State group's de facto capital, Raqqa, in northern Syria.
WHAT COULD GO WRONG?
The Americans are stepping into a crowded space in northern Syria, where US-backed Kurdish groups, Turkish and Russian troops, Syrian government forces and Islamic State militants are all within firing range of one another.
In Syria, US forces do not have a national military to partner with - unless Washington made a dramatic reversal and overtly partnered with Syrian President Bashar al-Assad.
Though no decision has been formally announced, the US is likely to partner with the SDF, which is dominated by Kurds, though it includes some Arab fighters and other ethnicities.
The US-backed group has proved to be the most effective fighting force against IS in Syria, moving in past months to isolate Raqqa and cut off supply lines.
But it is still seen as ill-equipped for the difficult assault on militants entrenched in the city.
By backing the Kurds in Raqqa, even a perceived lean toward Moscow and Damascus could bring a backlash from fiercely anti-Assad factions on the ground, threatening to draw American troops into the wider civil war in Syria.
- With AP