Defense Secretary Ash Carter and defense ministers from 12 other nations participating in the counter-ISIS ministerial meeting were quick to laud recent battlefield progress against the terror group.
But many questions remain about the future of the ISIS fight. Chief among them is what the future leadership of that effort will look like.
Carter, however, reassured his allies on the stability of the effort going forward.
"I do have confidence in the future of the coalition campaign," Carter said at a news conference following the summit. "It's logical, it makes sense, and therefore I expect that that logic will recommend itself to the future leadership of the United States."
Two US defense officials told CNN ahead of the gathering that the impeding political transition in Washington would be a focus of the summit.
"The core military contributors (are) interested in what comes next, interested in how the strategy might change, and interested in what that means for the coalition," a senior defense official told reporters en route to the summit.
A sudden change in tactics by the Trump administration -- such as collaboration with Russia and its Syrian client Bashar al-Assad -- could potentially derail the anti-ISIS coalition, as many of its members would oppose this teaming up.
Trump and his pick for national security adviser, retired Gen. Michael Flynn, have spoken positively of such a collaboration in the past. And Trump has just tapped Rex Tillerson, CEO of ExxonMobil and a man who was once awarded the order of friendship by Russian President Vladimir Putin, as his secretary of state.
Scenes this week of Assad's forces shelling eastern Aleppo as his troops seized the last few Syrian rebel holdouts Tuesday drew sharp condemnations from many of the governments attending the London conference.
"The dictator's militias have carved paths of destruction through crowded streets -- destroying hospitals, severing water supplies and herding thousands of people from their homes," UK Foreign Secretary Boris Johnson told Parliament Tuesday.
Speaking alongside Carter, UK Defense Secretary Michael Fallon also had harsh words for Assad and Russia, calling Aleppo "a tragedy of Russia's making."
Carter and Fallon indicated they didn't want to engage in the "hypothetical" prospect that Trump would seek to work with Assad to fight terrorism in Syria and thereby jeopardize the anti-ISIS coalition.
But Fallon did say, "That doesn't sound to me to be very likely."
Appearing on the BBC this week, Fallon said he was looking forward to working with Carter's designated successor, retired Marine Gen. James Mattis, noting that he was well known from his time as a NATO military commander.
Fallon predicted that Mattis would be strong in the face of Russian aggression, adding that Moscow was "a strategic competitor to us in the West" and they're could be no grand deal with Russia in Syria.
A key objective of Thursday's summit concerned obtaining additional resources that the military effort will need from national governments in the days ahead.
"Most of these countries require parliamentary approval for their deployments so there needs to be an understanding of where the vision is, what we are aiming towards," a defense official said ahead of the summit.
Carter and Fallon said that some of the nations in attendance agreed to fill gaps in capabilities by boosting their contributions, but they would not get into specifics.
Topping the wish list is additional strike aircraft and aerial refueling planes, as well as changes to the types of training being provided to local forces so that it focuses less on traditional basic military training and more on the development of "hold" forces, such as police that can govern areas recently recaptured from ISIS, also known as ISIL.
"You need hold forces that can keep the city out of ISIL's hands once the army ultimately departs," the defense official said, adding that changing national training missions often require legislatures to adjust the mandates governing their troops in Iraq.
And the US is not the only country on the verge of major political shakeups.
"Bear in mind, we're not the only ones that are going to be going through a political transition. France has upcoming elections in the near term, and (so do) several other countries," a second senior defense official told CNN.
All this political uncertainty comes just as the coalition has made significant progress in recent days in the fight against ISIS and is at a crucial point in the campaign
During recent stops in Afghanistan, Bahrain, Iraq and Italy, Carter repeatedly trumpeted the coalition's success against ISIS, citing the recent targeted killing of three ISIS leaders and the ejection of ISIS from Sirte, Libya, once the terror groups largest stronghold outside Syria or Iraq.