The Turkish army announced that two of its soldiers were killed on board of a helicopter, which was shot down during Turkeys ongoing Operation Olive Branch in Afrin. Afrin region is the area where the Turkish army along with its allied factions from the Free Syrian Army continue their Olive Branch operation, which entered its fourth week on Saturday. The campaign followed Ankara’s promises to “strangle” the new Border Security Force (BSF) in Syria. Turkish President Recep Tayyip Erdogan held the Syrian Kurdish Peoples Protection Units (YPG) accountable for the incident, promising a harsh response. “One of our helicopters was downed just recently,” Erdogan said as he spoke at a ruling Justice and Development Party’s (AKP) provincial meeting in Istanbul. “These things will happen, we are in a war,” the President said, adding that even though Turkey “might lose a helicopter,” the perpetrators of the attack will “pay a heavy price.” Erdogan also said the Turkish Armed Forces “destroyed many missile depots” of the Kurdish militias they are battling in the Afrin region. “We will continue to defeat the terrorist organizations that threaten the security and safety of our borders,” he added. "We have neutralized 1,142 terrorists, and our armed forces are achieving great successes and protecting the borders of the country,” Erdogan noted. In a statement, the Turkish General Staff said one of the ATAK helicopter crashed at around 1 P.M. (1000 GMT) during the ongoing operation in Afrin. The downed helicopter was a T129 ATAK helicopter, and it was shot down in Kirikhan district of Hatay province, killing two soldiers, Prime Minister Binali Yildirim told reporters in southwestern Mugla province. Yildirim said it remains “unclear" why the helicopter went down and added that an investigation had been launched. On the other hand, US National Security Adviser H.R. McMaster arrived in Istanbul on Saturday to carry out a series of meetings with Turkish officials. The meetings will focus on regional developments and Olive Branch operation, which was launched by the Turkish forces against terrorist organizations.