The incident Saturday killed Sgt. Leandro Jasso, 25, in Nimruz province's Khash Rod district.
There was no official confirmation of the circumstances of the blast but Ghazni has been one of the most heavily fought over regions of Afghanistan this year and many areas close to the city are in the hands of the Taliban.
United States military casualties in Ghazni should come as no surprise, as USA forces have stepped up operations in the province as security there has deteriorated over the past year.
Just the previous day, three USA service members were killed and three more were wounded in an explosion near Ghazni.
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Jasso, a member of the elite Rangers who was on his third deployment to Afghanistan, was accidentally shot by an Afghan partner force during a battle with al-Qaeda, the North Atlantic Treaty Organisation mission announced Tuesday.
The United Nations, which is co-hosting the summit at the city's Palais des Nations with the Afghan government, said the conference "will also be crucial in measuring results against the $15.2bn committed by the worldwide community for Afghanistan in 2016". The US military was forced to send combat forces, advisers, air support and other enablers to help the struggling Afghan military regain control of the capital.
The Taliban has claimed the attack that killed three USA service members and completely destroyed a US tank in eastern Afghanistan, AP reported.
In the past several weeks, the insurgents also have launched assaults on villages in rural districts of the province that are populated by minority ethnic Hazara Shiites.
The Taliban routinely reports on its operations in Ghazni on its official propaganda website. The group claimed responsibility for the attack, but they're not the only enemy. Earlier this month, US Gen. Scott Miller, the head of US and North Atlantic Treaty Organisation forces in Afghanistan who survived an October firefight in Kandahar, was photographed carrying a fully loaded M4 carbine assault rifle while visiting the Ghazni area. Of Afghanistan's 34 provinces, Ghazni was the only one not capable of conducting the election.