He also faced questions about whether Canadian special forces soldiers have curtailed trips to the frontline in the aftermath of a friendly fire death almost two months ago.
The prime minister said he wasn't going to talk about operational details and suggested the two sides are trying to move on from the painful episode which saw Canadian and Kurdish officials pointing fingers at one another over Sgt. Andrew Doiron's shooting death.
"It was a terrible tragedy," said Harper, who indicated that he had not yet read the report into the confused nighttime shooting.
"We'll get the facts, but let it not obscure, frankly, the respect I think we should have for the Kurdish fighters in this area. Back last summer when ISIS was literally overrunning this entire country with virtually no resistance at all these were the people who stood up and resisted them and stopped them."
Gen. Didawan Tafiq, a commander with the Zerevani Peshmerga, echoed the Harper's comments.
"Just a few kilometres from here is the ISIS terrorist," the general said through a translator. "We Pesh on the ground with the help from the coalition forces (and) Canadians we are keeping them away from coming into this region also and spreading into the world."
Tafiq also apologized for the incident, saying they'd "lost a friend" and it was a "miscommunication."
Harper's surprise visit took place about 40 kilometres west of Erbil and after whirlwind trip through Baghdad. It came just over a month after his government extended and expanded the combat operations involving the country's CF-18 jetfighters and the training mission undertaken by 69 special forces troops.
It was a picture perfect photo-op for Harper, who stood on a berm with binoculars overlooking rolling sun-baked fields with smoke wafting in the distance from grass fires near extremist trenches.
Harper made the journey under the watchful eye of special forces, who by virtue of the presence of the prime minister's entourage of media, were forced to partially peel back the thick blanket of secrecy that cocooned their deployment since it was ordered last fall.
While in Erbil, Harper received a warm welcome from Massoud Barzani, president of the Kurdistan region, and Nechivan Barzani, the prime minister of the regional government.
He met Iraq's prime minister, Haider al-Abadi, earlier in the day.
The separate welcomes, aside from being a reminder of the fractured nature of this country, could also have not been more different in tone.
The visit to Baghdad seemed strained and marred by tension with Iraqi officials, who'd been insisting Harper appear at a joint media availability with al-Abadi. The two sides settled on brief, perfunctory photo-op statements.
But the mood was more relaxed and friendly in the Kurdish capital, which buzzed with construction projects and calm, secular prosperity that seems to thrive even in the face of the fire-breathing threat of ISIL.
The federal government announced an additional $139 million in humanitarian aid to be spread around not only Iraq, but Syria, Jordan and Lebanon to help alleviate the burgeoning refugee crisis precipitated by the rise of the Islamic State.
An additional $26 million was pledged for stabilization and development. And over $1.9 million was set aside to buy the peshmerga bomb disposal robots and night vision goggles.
Harper visited a church that's benefited from Canadian aid dollars and a Montreal-based business that's injecting economic life into the city.
His visit to the war zone, made ahead of his planned attendance at celebrations in Europe marking the 70th anniversary of the end of the Second World War, was conducted under a blanket of tight security and a partial media blackout.
The U.S.-led international coalition, which has been conducting an air campaign to support Iraqi and Kurdish forces, as well as provide badly needed training, has been insisting for months that the advance of extremists had been checked.
American, British and Australian troops have been re-training the Iraqi army after it effectively melted away in the face of the ISIL advance last summer, and it was widely expected those refreshed forces would go on the offensive either this spring, or summer.
Aside from the special forces, Canada has also contributed six CF-18 jetfighters, a CP-140 Aurora surveillance plane and a C-150 Polaris tanker to the coalition bombing campaign.
There are persistent concerns about the influence of Iran over al-Abadi's government, fears that were heightened with reports in March that the regime in Tehran had deployed advanced rockets and missiles to help the Iraqis retake Tikrit.
That battle saw as many as 30,000 Iranian-trained militia fighters turned loose on the key, Sunni-dominated city.
Much of the blame for the rise of ISIL has fallen on Abadi's predecessor, Nuri al-Maliki, whose brutal, repressive policies alienated vast segments of the Sunni population.
Recently, al-Abadi sacked some of the political generals appointed by Maliki, chose to accept American military advisers and cut two deals with the Kurdish regional government over oil.
Ken Pollack, of the Brookings Institution, wrote recently that those are among some of the hopeful signs and speak to the Iraqi prime minister's "determination to do the right thing."
Also on HuffPost