OZAN KOSE/Getty Images Turkish police cordon off an area in Istanbul. A deadly bombing claimed by the self-described Islamic State killed at least 10 people in the city on Tuesday.

The suicide bombing that killed 10 German tourists in the heart of Istanbul on Tuesday is the latest outburst in a nearly yearlong spate of violence in Turkey.

In the past 12 months, the country's security situation has deteriorated against a backdrop of political turmoil and the continually deepening conflict in neighboring Syria.

Islamic State militant-linked terror attacks, including the most recent bombing on Tuesday, have killed over a hundred people, and clashes have escalated between Turkish government forces and the separatist militants of the Kurdistan Workers' Party (PKK).

Anadolu Agency/Getty Images Turkish Prime Minister Davutoglu mourns at the location of a terror attack that killed at least 10 in Istanbul on Tuesday. The bombing seemed to be aimed at killing tourists.

Turkey vs. Islamic State Militants

After months of international criticism for failing to take adequate action against Islamic State fighters in Syria, Turkey altered its policy in July and started to allow U.S. warplanes to use the country's air bases to launch airstrikes against IS militants.

The dramatic shift came after an IS-linked bombing in the city of Suruc killed 32 youth activists -- the first mass killing by the extremist group on Turkish soil.

While the policy shift won applause from the U.S., it also drew retaliatory attacks from the militant group. The shift from Turkey's hands-off approach to a more active role meant that IS has increasingly sought to target locations within Turkey, according to analysts.

Islamic State militants targeted Turkey again in October, when an explosion at a largely Kurdish peace rally in Ankara killed over 100 people in the worst terror attack in the nation's history.

Since then, Turkey says it has foiled multiple suspected IS bomb plots, including an alleged attempt to carry out a suicide attack on New Year's Eve revelers in Ankara. But authorities could not prevent Tuesday's bombing, which, like the NYE plot, seemed to deliberately aim to kill tourists.

“This one is different, in that it’s not attacking Kurdish-related targets like the previous four [bombings] but is going after foreign nationals or tourism-related targets in Istanbul," Aaron Stein, a senior fellow at the Atlantic Council, told The WorldPost. "It points to a change in the ISIS strategy of how it treats Turkey and plans to attack Turkey.”

Turkey vs. The PKK

Turkey's leaders have made clear that in their view the PKK and IS are equal as threats and enemies of the state. In an address in October, President Recep Tayyip Erdogan stated that there was no difference for Turkey when it came to the groups.

Turkey and the Kurdistan Workers' Party have been in violent conflict since at least the early 1980s. The PKK originally wanted an independent state for the Kurdish people -- that aim has since been dialed back -- and pursued it through an armed insurgency against the Turkish state.

The PKK went into decline after the capture of its leader, Abdullah Ocalan, in 1999, and the group shifted towards a peace process in the 2000s. This finally resulted in a ceasefire in 2013, as well as the hope for negotiations that would result in a comprehensive peace agreement.

Kurdish anger towards the Turkish government's lack of support for Kurds in Kobane, Syria, strained attempts at peace. In June of last year, an IS-linked bombing in the predominantly Kurdish city of Diyarbakir further inflamed tensions between Kurds and the government.

Anadolu Agency/Getty Images Turkish soldiers patrol the town of Cizre. Major fighting between the state and PKK militants has resulted in hundreds of deaths.

Initially, IS attacks in Turkey were aimed at Kurdish targets, as part of the conflict between the Kurds and the extremist group that was being fought in Iraq and Syria.

Critics of Erdogan contended that he and his ruling AK Party were ignoring IS threats because the group was also fighting with the PKK, Turkey's enemy, as well as posing a threat to the regime of Syrian President Bashar Assad, Turkey's other enemy.

“A large minority of the Turkish public believes there is silent AKP support for the Islamic State,” Stein said.

Following the attack in Suruc last July, a PKK-linked bombing killed two Turkish soldiers amid anger that the government hadn't done enough to protect against the IS-linked assault.

Anadolu Agency/Getty Images A soldier looks out over Cizre district after the government carried out an anti-terror campaign against the PKK there. Turkey's leaders have made clear that in their view, the PKK is as equal a threat as IS.

The government responded to the attack with airstrikes against PKK positions in northern Iraq, and as more fighting erupted between the state and the militant group in late July, Erdogan stated that the peace process was impossible.

Since the PKK bombing and Erdogan's airstrikes, areas of southern Turkey have been rife with violence between PKK and the state. The government has imposed curfews on some largely Kurdish towns in the southeast, resulting in protests that have led to demonstrator deaths in clashes with security forces.

In December, Erdogan vowed to "annihilate" the PKK and the government launched a large-scale military offensive in southern towns. Turkish tanks shelled PKK positions in the town of Cizre, and as many as 10,000 troops and officers were deployed in that town and neighboring Silopi district.

Members of the HDP, a pro-Kurdish political party, say that the army is destroying towns and claim at least 72 civilians have been killed in the fighting since the start of the offensive. Erdogan has said that over 3,000 PKK militants were killed last year. The situation threatens to spiral even deeper, as government raids last week resulted in the arrest of HDP members and clashes on Friday killed a police officer in the south.

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