Syria was on the agenda along with energy and trade issues as Putin makes first visit outside Russia since October.Russia and Turkey cannot agree on how to respond to the Syrian conflict, Russian President Vladimir Putin, who is in Istanbul for talks with the Turkish Prime Minister Recep Tayyip Erdogan, has said. "Russia and Turkey for the moment cannot find a mutual approach on the methods of how to regulate the situation in Syria. But our assessment of the situation completely coincides," said Putin during a press conference with Erdogan on Monday. Erdogan told Putin that Russia should stop supporting the regime of Syria's Bashar al-Assad, a claim Putin denied. "We are not defenders of the existing regime in Syria, I have already stated this, we are concerned about something else, we don't want to repeat the mistakes of past." Russian-Turkish tensions came to a head in October when Turkey intercepted a Syrian plane en route from Moscow to Damascus on suspicion that it had military cargo, drawing an angry response from Russia. Erdogan says the Turkish and Russian foreign ministers will work together more intensively on the Syrian problem. Patriot missiles Russia also objected to Turkey's request to NATO for the deployment of Patriot missiles on its volatile border with Syria. It warned that such a move could spark a broader conflict that would draw in the Western military alliance. Putin told the joint press conference that the deployment of US-made Patriot missiles with war-ravaged Syria would worsen tensions. "Creating additional capabilities on the border does not defuse the situation but on the contrary exacerbates it," said Putin. But Turkey insists the US-made Patriots would be used for purely defensive purposes. Dimitri Peskov, who is Putin's spokesman, told Al Jazeera that there were differences over Syria between the two men. "Turkey says Assad’s regime should go. We say if Assad leaves, the tens of thousands of refugees in Turkey right now will increase to hundreds of thousands. There will be a gap in the government and there will be lots of blood on the streets. This is what we say". Protesters had chanted anti-Putin slogans outside Erdogan's office and another demonstration was staged outside the Russian consulate in Istanbul before the two leaders began their meeting on Monday. Trade links Despite their differences on some thorny political issues, Russia and Turkey enjoy growing trade and energy links. The trade volume between the two countries is expected to reach $35bn by the end of this year. Turkey depends on Russia for most of its natural gas and oil supplies. In 2010, Ankara struck a deal with Moscow to build the country's first nuclear power plant at Akkuyu in the southern Mersin province. Putin told the press conference that his country would finance the total cost of the plant. Russian state company Rosatom is set to construct the 22-billion-dollar plant. It is expected to be completed by 2022. It is Putin's first trip outside Russia since he visited Tajikistan on October 5 and follows speculation that the normally globe-trotting leader is having health problems.