Six Iraqi security personnel and three civilians were killed in an ambush Saturday carried out by ISIS north of Baghdad, police and a local official said.
And in Nigeria a further five people were killed by Islamic State West Africa Province (ISWAP) fighters.
An Iraqi police source said a roadside bomb hit a car and that jihadists opened fire on a rescue team of policemen and state-aligned paramilitary forces when they arrived at the scene, about 200 kilometres (120 miles) from the capital.
Four members of the Hashed al-Shaabi and two policemen died along with three civilians, Mohammed Zidane, the mayor of Zouiya, 50 kilometres from the city of Tikrit, told AFP.
There was no immediate word of casualties among the assailants but Mr Zidane said those killed among the Hashed, a coalition of mainly Shiite forces, were Sunni tribesmen.
Both the mayor and police said the ambush was the work of ISIS jihadists, although no immediate claim of responsibility was issued.
ISIS swept across a third of Iraq in 2014, seizing major cities across the north and west and reaching the suburbs of the capital.
After a fierce three-year fight backed by a US-led military coalition, Iraq declared the group defeated in late 2017.
The coalition has significantly drawn down its troops this year and ISIS sleeper cells have continued to wage hit-and-run attacks in desert areas where troops are stretched thin.
Attacks with high tolls and close to the capital have been rare, however.
The latest attacks come as the United States announced that it will withdraw another 500 troops, reducing its deployment to 2,500 soldiers. Numbers were already depleted from an even greater reduction made just a few weeks ago in September.
Five dead in Nigerian ambush
Iraq wasn't the only country to be assailed by ISIS on Saturday. Jihadists killed five Nigerian soldiers and an allied militiaman in an ambush on a military convoy in Nigeria's restive northeast Borno state, three security sources said.
Islamic State West Africa Province (ISWAP) fighters armed with machine guns and rocket-propelled grenades opened fire on a convoy of soldiers and an anti-jihadist militia in Kwayamti village, 60 kilometres (36 miles) north of the regional capital Maiduguri, they said.
"Five soldiers and a militiaman were killed in the ambush," one of the security sources told AFP.
Four members of the militia force were seriously wounded in the attack which occurred around 1600 GMT, according to two other sources who gave the same toll.
The convoy was on its way to the town of Baga on the shores of Lake Chad, some 140 kilometres away, as a security detail for the state governor, Babagana Umara Zulum who flew by helicopter earlier in the day.
This map shows the loci of both Maiduguri (red) and Lake Chad (green).
All the sources asked not to be identified because they were not authorised to speak on the incident.
Zulum was in Baga to distribute food to residents who returned to the fishing town two months ago, six years after they fled a deadly jihadist raid, said the sources.
Local authorities have been encouraging people displaced by the jihadist uprising to return to their homes, saying feeding them in the camp was no longer sustainable, despite concern from aid agencies that it was not safe to return.
ISWAP, which split from the main Boko Haram faction in 2016, keeps its camps in islands on Lake Chad - where Nigeria, Niger, Cameroon and Chad meet.
In September, at least 30 security personnel were killed when ISWAP attacked Zulum's convoy near Baga but he escaped unhurt.
At least 36,000 people have been killed and around two million displaced in the decade-long conflict in Nigeria's northeast.
The violence has spilled into neighbouring Niger, Chad and Cameroon, prompting the forming of a regional military coalition to fight back.
The National analysed the renewed threat of ISIS in a four-part special: ISIS regenerates.
The series dissected the group's strategy for global growth, explored its use of obscure social media platforms, looked at how it is operating on a military level in Africa, and revealed how it is profiteering from elephant poaching and the gems trade.