The attack bore all the traits of Islamic State in Iraq. A small unit of militants, armed with Kalashnikov rifles and suicide belts, hit the Tripoli prison just before sunrise.

Blasting though a wall, four fighters worked their way through the heavily guarded compound before firing a rocket-propelled grenade to breach the cells inside.

Their target, security sources say, was a jailed Libyan Islamic State militant. Clashes erupted. Two of the attackers, a Moroccan and a Sudanese, detonated suicide belts and shortly afterwards all four, and the militant, were dead.

The prison break failed. But it was another illustration of the tactics employed by an Islamic State front determined to emulate the success of the group’s founders in Iraq and Syria.

“When we see them fighting, they are well trained. There were only four, but they destabilized the whole base,” said Muaad Khalil, a spokesman for forces at the Maitiga base. “Who would have thought to attack this base, but they did.”

Four years after the overthrow of Muammar Gaddafi, Libya is locked in a conflict between two rival governments — an official one in the east, and a self-declared one controlling Tripoli — and the many armed factions that back them.

Far from the battlefields of Iraq and Syria, Islamic State has steadily grown in Libya’s chaos, controlling the city of Sirte, and worrying Western governments who fear it can only become stronger in the post-revolution mess.

They have left their mark on the North African state. They have massacred Christian Egyptians on a Libyan beach, publicly flogged criminals in Sirte, stormed oilfields, and attacked a five-star Tripoli hotel.

But while Libya’s turmoil and history of jihadism offered fertile ground, Islamic State has run up against the heavily armed factions and rival Islamists already in place.

Even as they lay claim to Sirte, Libya’s Islamic State followers have been ousted from Derna city by local fighters, and have shown they cannot hold ground or muster the finances and oil resources they benefit from in Iraq.

“They clearly want to expand from Sirte,” one Western diplomat said. “They continue to maintain the ability to carry out one-offs outside their main area, but they are still small.”