Islamic State militants attacked Kurds across northern Iraq on Friday. The wave of attacks came days after Kurdish fighters said they had taken full control of the northern Syrian town of Kobanî following a four-month battle.

Police in Kirkuk said the Islamists had launched mortars and attacked positions of Kurdish forces in four districts. Fighting was reported southwest of the city. A car bomb exploded at a hotel in the center of Kirkuk and seven Kurds were killed in a suicide bombing at a checkpoint near Jalawla, a town southeast of Kirkuk.

Kurdish military sources told reporters the peshmerga had repelled dawn attacks at different points along a more than 1,000 kilometer frontline.

The Kurds took Kirkuk in June last year, taking advantage of the central government’s inability to stem the advance of Islamic State insurgents. The group conquered Mosul, Iraq’s second largest city, situated to the northwest of Kirkuk, without much army resistance that same month, triggering a bloody sectarian conflict that spans the eastern half of Syria and the northwest of Iraq.

An offshoot of the international terrorist organization Al Qaeda, the Islamist group has proclaimed a caliphate in the areas it controls and battles both the Iraqi government in Baghdad and the regime of President Bashar al-Assad in Syria.

The United States and Arab and Western allies launched airstrikes against Islamic State targets in August. European countries have also supplied the semi-independent Kurdistan Regional Government in the north of Iraq with combat equipment.

However, Kurdish commanders complain they remain ill-equipped compared with the militants who plundered Iraqi army depots when they overran Mosul.

With the exception of the siege of Kobanî, during which Islamic State militants battled Syrian Kurdish fighters for months, the group has concentrated more on engaging Iraqi security forces and Shia militias further south and west in the last few months.

The conflict between the Islamic State and the Kurds underlines the growing insignificance of the border between Iraq and Syria.

One of the Islamic State’s objectives is to erase the frontier, drawn a century ago by European imperialists, and unite the Sunni Muslims living roughly between the Euphrates and Tigris Rivers in one country.

The Kurds, the world’s largest stateless nation, are scattered across Iraq, Syria and Turkey.

While Assad’s regime, fighting its own civil war against mainly Sunni rebels, has largely left the Kurdish minority in Syria alone, allowing it to start building state institutions, Turkey, which has the region’s largest Kurdish population, is apprehensive about the prospect of a Kurdish state emerging — even as it backs autonomy for Iraq’s Kurds who are supplying it with oil.