President Recep Tayyip Erdoğan, responding to journalists' questions on his way back to Ankara from a one-day official trip to war-torn Ukraine, said on Saturday that Turkey supported the full implementation of the 12 February Minsk cease-fire agreement in Ukraine. Attending the fourth meeting of the Turkey-Ukraine High Level Cooperation Council, Erdoğan said that the Ukraine issue will be solved when both sides show determination to implement the Minsk ceasefire when asked whether Turkey would take on the duty of mediator in the current crisis. "They [Russia] want to see the implementation of the Minsk [ceasefire]. The same goes for [Ukrainian President Petro] Proshenko, too, as they say: 'Russia should abide by the Minsk Agreement.' But Crimean Tatars also have some problems, there may be another talk with Russia," he said.Erdoğan's visit to Kiev takes place at a critical time when the Ukrainian government troops and Russia-backed separatists have not completely set aside their arms. The ceasefire agreement that was signed on February 12 is precarious, despite a series of mediating talks and peace efforts. The Organization for Security and Co-operation in Europe (OSCE), which is monitoring the ceasefire, recently protested in recent reports that both parties hindered its observer teams from accessing weapons sites.Erdoğan said that Ankara was concerned about Meskhetian Turks and Crimean Tatars living in Ukraine and Crimea who, like the rest of society, bore the brunt of months of fighting between government forces and separatist rebels. Turks have close kinship bonds with the Muslim, Turkic-speaking Tatar minority in Crimea, the Black Sea peninsula Moscow annexed from Ukraine a year ago.Erdoğan said there is a nearly 8 percent loss of land in the Donetsk and Luhansk regions and added that the chief monitor of the OSCE Special Monitoring Mission to Ukraine, retired ambassador Ertuğrul Apakan, and nearly a thousand members have been monitoring the crisis in Ukraine.He pointed out that Western countries have pledged 5 billion euros ($5.4 billion) of aid and that it is estimated that 1.7 billion euros will be provided this year.Pointing out that there would be a meeting over the Ukrainian crisis among donor countries, he said that Turkey has the capacity to cooperate with Ukraine on the grounds of politics, military, economy, trade and culture."There are nearly 600 Turkish businessmen in Ukraine now, and the trade volume [between the two countries] is around $4 billion," he added.He said that the defense industry was on top of the agenda during his talks in Ukraine."We also brought the energy issue to the table. They considered the Turkish Stream as a political reaction. But when we discussed the issue with [Russian President Vladimir] Mr. Putin, Ukraine did not come into question," said Erdoğan, adding that Turkey's biggest supplier is Russia.Erdoğan: Presidential system is necessaryErdoğan also touched on the benefits of switching to a presidential system, saying that the presidential system will be shaped in accordance with Turkish culture. "Let's establish a new constitution and bring a presidential system. We cannot solely be a spectator at the tribune. The current [parliamentary] system does not fit. It was established in line with the needs of an old Turkey," Erdoğan said.Slamming those who say a presidential system in Turkey could lead to dictatorship, Erdoğan continued: "They too know a presidential system cannot be deemed a dictatorship. This nation would not allow those who aspire for one-man-rule."