Türkiye struck several targets in Syria on Tuesday after President Recep Tayyip Erdogan issued new threats to launch a ground operation "soon" against Kurdish fighters despite calls for de-escalation from Washington and Moscow. Ankara launched a series of air strikes in Operation Claw-Sword on Sunday -- hitting dozens of Kurdish targets across Iraq and Syria -- and announcing that its military was once again "on top of the terrorists". The air raids followed a bombing in Istanbul on Sunday that killed six people and wounded 81. Türkiye blamed the attack on the Kurdistan Workers Party (PKK), which is blacklisted as a terror group by the European Union and the United States. The Turkish leader has threatened a new military operation into northern Syria since May and upped those threats in the wake of this months attack. "We have been on top of terrorists for a few days with our planes, cannons and drones," Erdogan told a ceremony in the Black Sea province of Artvin. "God willing, we will root out all of them soon with our tanks, artillery and soldiers." The PKK, which has waged an insurgency against the Turkish state since 1984, denied any role in the November 13 bombing -- the deadliest in five years after a spate of attacks in Türkiye between 2015 and 2017. - Child among the dead - On Tuesday evening, Turkish artillery shelling continued on the city of Kobane in northern Syria, controlled by the Kurdish-led Syrian Democratic Forces (SDF). Earlier a Turkish drone strike hit a base in northeast Syria used by Kurdish forces and the US-led coalition, the Kurds and a war monitor said. Two SDF fighters were killed, a spokesman for the group said, but no US troops were there or in danger, according to the US Central Command. Centcom spokesman Colonel Joe Buccino said "We oppose any military action that destabilized the situation in Syria." Five civilians were killed and three others seriously wounded in northwest Syria Tuesday when rockets were fired at a city controlled by Turkish proxy forces, the war monitor said. A child was among the dead when rockets targeted a market in Azaz, the Syrian Observatory for Human Rights said. Turkish drone strikes also hit a small oil field near the border town of Al-Qahtaniyah, an AFP correspondent reported. The war monitor confirmed the strikes. -De-escalation- The United States late Monday urged de-escalation and Russia said Tuesday it hoped Türkiye would exercise "restraint" and refrain from "excessive use of force" in Syria. "We understand and respect Türkiye’s concerns regarding its own security... We still call on all parties to refrain from steps that could lead to seriously destabilizing the situation," Kremlin spokesman Dmitry Peskov told reporters. Germany and France have also called on Türkiye to show restraint and act in a "proportional" manner Erdogan said his government knew "who protects, arms and encourages those terrorists", in a veiled reference to Washington, which relied heavily on Syrian Kurdish forces in the fight against the ISIS group. He said Türkiye had been patient enough, "not because it was desperate", but because it was loyal to diplomacy. "The road has come to an end for those who think they can keep Türkiye waiting by playing with letters and changing the name of the terrorist organization," said Erdogan. His Interior Minister Suleyman Soylu said that the Kurdish fighters wanted to establish "a terrorist state around us, we could not allow that. Protecting our borders and our nation is our responsibility and duty,". In Syria, the principal target of the Turkish campaign is the Kurdish Peoples Protection Units (YPG), who dominate the SDF. Washington forged a close alliance with the SDF during their successful campaign to oust ISIS from Syrian territory. But Ankara regards it as a terror group linked to the PKK. -Robust campaign- Erdogan has repeatedly called for a 30-kilometer (19-mile) "safe zone" to protect Türkiye against cross-border attacks from Syrian territory. At least three people, including a child, were killed in a Turkish border town Monday by a rocket fired from Syria. Anthony Skinner, a Türkiye expert and a political risk consultant, told AFP conditions "are in place for a particularly robust campaign" against Kurdish fighters ahead of Turkish presidential and parliamentary elections in June. "Erdogan wants to bolster support for his AKP and its (nationalist) MHP allies, so he is playing the nationalist and security card. Hence the noise," he said. "Erdogan effectively used the security and stability cards in the run-up to the re-run of the general election in 2015. But his work is cut out now because of economic and socio-economic pressures."