Though officials warn that military action will continue for some time, they are generally upbeat about the progress and quickening momentum of the fight.
After months of brutal, street-by-street combat, Isis has now lost control of most of its stronghold of Mosul in Iraq, while the jihadists have become largely isolated in their Syrian bastion of Raqqa.
Pentagon chief Jim Mattis and his Danish counterpart Claus Hjort Frederiksen are among the senior leaders from 15 countries attending Tuesday's summit.
“We're going to look to the future, determine what more is needed, if anything,” Mattis told reporters ahead of his arrival in Denmark.
In addition to military issues, the summit is also likely to touch on areas such as propaganda on social media and financing of terror, according to an expert from Denmark’s military academy Forsvarsakademiet.
“The countries involved in the operation [against Isis] will be getting together to assess how far they are in the process of destroying Isis,” Peter Viggo Jakobsen told DR.
The choice of Denmark as the location of the summit reflects the good relationship the Scandinavian country has with Washington, Jakobsen added.
Several coalition countries are keeping a nervous eye on the region as Isis-held territory diminishes.
Thousands of foreign fighters remain in Iraq and Syria, and coalition nations — particularly in Europe — are bracing for a possible wave of battle-hardened jihadists returning home.
According to a senior US administration official, Interpol has identified 14,000 foreign fighters it knows has travelled to Syria and are still alive.
The largest numbers come from Tunisia, followed by Saudi Arabia.
Thousands more have travelled from Europe, including 100 or so from Denmark, the official, who asked not to be named, told AFP.
The international law enforcement agency Interpol is now part of the anti-IS coalition, becoming the alliance's 68th member.
The campaign against Isis began in autumn 2014 and has seen the Iraqi security forces — backed with coalition training and air power – reverse humiliating losses and recapture several key cities including Ramadi and Fallujah.
Iraq's second city Mosul is now mainly back under Iraqi control, though Isis continues to hold the Old City on the west side, where its fighters are preparing for a bloody last stand.
In Syria, coalition-backed Kurdish and Arab forces have been gradually recapturing towns and villages, with the focus now on isolating Raqqa ahead of a major offensive to seize back the city after more than two years of jihadi rule.
US President Donald Trump came to power on a pledge to destroy Isis.
Though much of the groundwork had already been laid and the coalition had conducted thousands of strikes, US military leaders credit Trump with delegating them greater authority, enabling a quickening pace of operations.
Critics say the additional strikes have accelerated the rate of civilian deaths.
The administration official said one request for the coalition would be for more de-mining support to help clear areas abandoned by Isis.
The jihadists have rigged explosives to homes, buildings and even the doors on people's cupboards, and clearing these bombs and mines is a massive undertaking.
Officials also want quicker access to funds and resources to help with stabilising and protecting areas after Isis has left.