ISTANBUL (Reuters) - Turkey’s military dropped commandos on mountain ridges in a new operation against Kurdish militants based over the border in northern Iraq, the defense ministry said on Tuesday.

The push began with artillery and air strikes on Monday afternoon, and the operation by commando brigades began that evening, according to a ministry statement.

It said the operation targeted Iraq’s Hakurk region, just across the border from Turkey’s southeastern tip, which also borders Iran. The Kurdistan Workers Party (PKK) militant group is based in northern Iraq, notably in the Qandil region to the south of Hakurk.

“With this operation, the aim is to destroy the caves and shelters used by the terrorist organization and neutralize terrorists in the Hakurk region,” the ministry said.

Video published by the ministry showed helicopters landing commandos on mountainous terrain. It also shared photos showing shells fired by howitzers and soldiers perched on ridges, surveying hillsides with their rifles.

“The operation, with the support of our attack helicopters, is continuing as planned,” the statement said. The military frequently launches air strikes against PKK targets in northern Iraq but ground operations are less common.

Nine militants were “neutralized” so far in the operation, the ministry said later in the day, using a term to refer to deaths, injuries or captures.

It added that shelters and ammunition depots were also struck in air strikes in Qandil and Zap, another nearby region.

The PKK launched an insurgency in mainly Kurdish southeast Turkey in 1984 and more than 40,000 people have been killed in the conflict. It is designated a terrorist group by Ankara, the European Union and United States.

There was no comment from the PKK on the operation.