For residents of Turkey's Kurdish-majority city of Diyarbakir, the thunderous boom of warplanes is all too recognisable, and was even before the Turkish army's most recent incursion into nearby Syria.<br/> Turkey launched Operation Peace Spring on October 9 to drive away the predominantly Kurdish Syrian Democratic Forces from its border, and for Turkey's Kurds it was the latest extension of a war that has raged in their communities since 2015. With the aim of building a buffer zone where they could return some of the more than 3.3 mainly Arab refugees the country has hosted since the Syrian civil war erupted in 2011, the assault was triggered by US President Donald Trump’s announcement that he was to withdraw troops from the region. Ankara has long accused Syria’s People’s Protection Units (YPG), which form the backbone of the SDF, of being an extension of the outlawed Kurdistan Workers’ Party (PKK), considered a terrorist organisation by Turkey, the US and European Union. Although separate in command structure, focus and leadership, they are both movements fighting for a common national cause and are ideologically shaped by Abdullah Ocalan, the PKK founder who was imprisoned by Turkey in 1999. Turkey also sees the autonomous Kurdish-led enclave in north-eastern Syrian known as Rojava as a threat to its security. The violence that erupted in spring 2015 in Turkey’s south-east between the state and the PKK is rooted in the group's insurgency that began in 1984, and which is commonly estimated to have claimed over 40,000 lives across both sides. However, it was the pro-Kurdish Peoples’ Democratic Party (HDP) gains in an election that cost President Recep Tayyip Erdogan’s Justice and Development Party (AKP) its parliamentary majority that was the catalyst for the current upsurge in violence. An escalating Turkish security force crackdown in south-eastern Kurdish communities followed, prompting an armed uprising by the PKK and its offshoots across Turkey, ending a two-and-a-half-year ceasefire. By the time voters went back to the polls the following November, the nascent peace process was scuttled and Mr Erdogan regained his majority. I travelled through Turkey’s Kurdish region as fighting raged in early 2016, covering what had become a brutal war between Turkish security forces and PKK guerrilla fighters and that largely escaped international scrutiny. I saw the people of Cizre, Nusaybin and Diyabakir’s old city, Sur, endure carnage. That February, photojournalist Lazar Simenov and I were the first foreign reporters granted access to the reconquered city of Cizre by Turkish security forces following a siege that lasted more than two and half months. Beyond the armoured vehicles and checkpoints, which had severed the city of roughly 125,000 people from the outside world, lay a wasteland of rubble and war-ravaged buildings. The rotting smell of decaying corpses that were still being pulled from the piles of shattered concrete hung over the city. Children kicked a ball over shell-damaged streets, littered with twisted metal and a resident pulled pieces of their home’s front wall from their living room. Locals pointed to where tanks and artillery had been deployed to the surrounding hills, raining shells on them for a week, and intense fighting in the streets followed — PKK guerrillas resisted the army with small arms and improvised explosive devices. They claimed hundreds of civilians were burned to death or blown apart in basements as they hid from Turkish bombardment. “Turkey may give us [Turkish] ID cards, but they attack us because we are Kurds,” middle-aged Cizre resident Ramazon Sakci told me at the time, standing in front of his bullet-riddled home. The wrecking of Cizre is a testament to what Turkey is willing to do in its pursuit of a military solution to demands for Kurdish autonomy, yet I saw similar determination from militants, from behind urban barricades built from ripped-up paving stones in Nusaybin. The town is located on the border, adjacent to Qamishli, Rojava's capital, and its young rebels looked to Syria’s Kurds for their inspiration. In the neighbourhoods gripped by rebellion, a system of sheets was strung up to provide cover from snipers, trenches were dug and a labyrinth of street barricades erected. Turkish drones watched from above, while Kurdish fighters reinforced defences and planned hit and run attacks on military and police. “We are not fighting to replace the Turkish State; we are fighting for rights and recognition,” a PKK commander told me there. “It’s OK if there are Turkish soldiers on the border, but not their police in our streets.” Within two months, the neighbourhoods had been raised to the ground after a sustained Turkish assault. The example set by Syrian Kurds when they had liberated their territory from both government control and ISIS was a powerful symbol for their counterparts in Turkey after the implosion of the peace process. As the YPG’s advanced in Aleppo’s countryside in 2016 under Russian air power, as they captured swathes of territory from the Turkish-backed Free Syrian Army, it was a time of both terror and optimism for them. In Diyarbakir’s bustling streets, where Turkish military bases and barracks carve out chunks of downtown, it was impossible then to ignore the Turkish water cannon trucks constantly patrolling, watching residents with suspicion. Protests calling for an end to military and police domination were violently swept off the streets, pushing young Kurds to see a future in the democratic experiment being tested over the border in Rojava rather than in talks with Ankara. The historic old city of Sur, which had been gripped by armed revolt, was, like Cizre and Nusaybin, engulfed in a war with the state. Despite defeats, the conflict continues to simmer four years on and the discontent of Turkey’s Kurds persists. The Syria operation has already claimed some of the Kurdish-controlled border territory and forced the YPG to partner with the Syrian government, putting an end to Kurdish self-emancipated local rule.