President Donald Trump's son-in-law Jared Kushner travelled with the top US general to an Iraqi base 10 miles (16 km) from Mosul on Tuesday, and voiced hope the city's eventual recapture from Islamic State would be "a victory for the world".
Kushner was on the second day of a trip to Iraq as the guest of Marine General Joseph Dunford, chairman of the US military's Joint Chiefs of Staff. The visit to the Hammam al-Alil base allowed them to get an operational briefing from Iraqi and US commanders.
The trip has demonstrated the far-reaching portfolio of Kushner, 36, who is part of Trump's innermost circle and who has been given a wide range of domestic and foreign policy responsibilities, including working on a Middle East peace deal. His views on Iraq could shape Trump's own opinions.
It comes as Trump is examining ways to accelerate a US-led coalition campaign that US and Iraqi officials say has so far been largely successful in uprooting Islamic State militants in Iraq and Syria.
Mosul is by far the biggest city ever to have been held by Islamic State, and winning it back would largely destroy the Iraqi part of the group's "caliphate", proclaimed from a Mosul mosque in 2014.
Although Trump campaigned on defeating Islamic State, he has not yet announced any major changes to war strategy. The Mosul battle, the biggest in Iraq since the US-led invasion in 2003, has been under way since October, with 100,000 Iraqi troops, Kurdish fighters and Shia militiamen seeking to drive out the militants with the support of US-led air strikes.
Speaking after lengthy battlefield reports from two Iraqi generals, Kushner sounded upbeat about the campaign and said the partnership between US and Iraqi troops was "very impressive". He also expressed hope that partnership would be enduring, signaling White House interest in longer-term US military assistance.
"I hope the victory that you have in Mosul in the near future will not just be a victory for the American and Iraqi troops but it will be a victory for the world," Kushner said.
On Tuesday, Islamic State issued its first official remarks referring to Trump since he assumed the US presidency in January, describing him as an "idiot".
"You (the US) are bankrupt and the signs of your demise are evident to every eye," spokesman Abi al-Hassan al-Muhajer said in a recording released on the messaging network Telegram.
"...There is no more evidence than (that) you being run by an idiot who does not know what Syria or Iraq or Islam is."
Kushner's trip is his first to Iraq and the visit to Hamman al-Alil, where US advisers and artillery are positioned to assist the battle in Mosul, was also the closest Dunford has got to Mosul since the campaign began.
Iraqi security forces are engaged in fierce, house-to-house fighting in Mosul. Nearly 290,000 people have fled the city to escape the fighting, according to the United Nations, and it has had a heavy toll on civilians trapped in the city.
The advance has been slowed since March 17, when scores of people sheltering from air strikes were killed in a blast. The United States has acknowledged it may have had some kind of role in the incident but also said Islamic State may be to blame. A US investigation is ongoing.
Dunford assured the Iraqi generals of continued US support despite the civilian deaths.
Although the loss of Mosul would deal a major defeat to Islamic State, US and Iraqi officials are preparing for smaller battles even after the city is recaptured and expect the group to go underground to fight as a traditional insurgency.