The Turkish government over the weekend demanded that Gen. Khalifa Haftar “immediately” release six Turkish nationals arrested in Libya to avoid a military response.

Ankara’s demand came as tensions between Turkey and Haftar’s Libyan National Army (LNA) intensified after the warlord’s troops announced that they had destroyed a Turkish drone parked in Tripoli’s only working airport on Sunday and arrested some citizens of Turkey.

In April, the LNA, which is fighting on behalf of the breakaway government based in eastern Libya’s Tobruk region, launched an offensive to take the capital of Tripoli from the United Nations-brokered Government of National Accord (GNA) headquartered there.

Haftar’s forces admitted to detaining two Turkish nationals over the weekend, Reuters reports. The Turkish government, however, placed the number of Turks arrested by Haftar at six and vowed to respond to any attacks on Turkish interests.

In a statement, the Turkish Foreign Ministry warned that it would consider Haftar’s “illegal militia forces” to be “legitimate targets” if the Turks are not liberated, France 24 reveals.

The “detention of six Turkish citizens by Haftar’s illegal militia in Libya is an act of banditry and piracy. We expect our citizens to be released immediately,” the Turkish foreign ministry reportedly declared, according to Turkey’s state-run Anadolu Agency (AA).

“Should this not happen, Haftar elements will become legitimate targets,” it added.

Earlier on Sunday, Turkish Defense Minister Hulusi Akar reportedly warned that there would be “heavy” repercussions to any “hostile attitude or attacks” by Haftar and his eastern forces.

The minister made those comments after an LNA spokesman deemed Turkish assets in Libya “legitimate targets,” accusing Ankara of helping rival fighters loyal to the GNA.

Reuters notes:

Haftar’s forces said they hit the drone in an air strike on Mitiga airport, part of a series of measures meant to punish Turkey for its support of the rival, internationally recognized Libyan government in Tripoli. … Haftar’s administration cut all ties with Turkey on Friday, banning its flights and ships from eastern Libya. It upped those measures on Sunday by declaring Turkish firms, imports, and even symbols illegal.

With the help of Russia, France, Egypt, and the United Arab Emirates (UAE), Haftar and his eastern forces have gained control of most of Libya. Meanwhile, Turkey has been lending support to the GNA, supplying drones and other military assistance to the internationally recognized administration of Prime Minister Fayez al-Serraj.

Since the U.S.-backed overthrow of Libyan dictator Muammar Gaddafi in 2011, the North African country has been engulfed in chaos with rival governments and their respective militias competing for powers as jihadi groups establish a foothold amid the unrest.

Haftar has accused Turkey of supporting jihadis who support the GNA in Libya.