Russian President Vladimir Putin heads to Turkey on Monday for a one-day trip focused on trade that is likely to be overshadowed by the two countries' differences over Syria.
The visit to Istanbul, Putin's first trip in two months, also is expected to address concerns over his health. The unusual break in his travel schedule has fed speculation that the 60-year-old Russian leader is suffering from serious back trouble or another illness. His spokesman has attributed Putin's discomfort to a pulled muscle, and the president has appeared more mobile in recent days.
During the talks, Turkey is certain to press Putin to stop backing Syrian President Bashar Assad. The Kremlin, however, has shown no inclination of relinquishing its support for its last Mideast ally, whom it has shielded from international sanctions and continued to provide with weapons amid an escalating civil war.
Russia and China have used their veto power at the U.N. Security Council to block any U.N. sanctions on Assad's regime over its crackdown on an uprising that began in March 2011. Advocates say at least 40,000 Syrians have been killed in the fighting since then.
Moscow also has insisted that it would honor weapons contracts signed earlier with Syria for the delivery of anti-ship and air-defense missiles. The Kremlin has argued that the Russian arms sales don't violate any international agreements and has rebuffed Western demands to halt the trade.
Russia reacted angrily in October when Turkey forced a Syrian passenger plane flying from Moscow to land in Turkey due to what Turkish officials said was military equipment on board. Moscow said the plane was legally carrying radar parts for Syria.
Yuri Ushakov, Putin's foreign affairs adviser, told reporters on Friday the plane incident may come up during Putin's talks with Turkish Prime Minister Recep Tayyip Erdogan. He signaled, however, that Russia was not going to press its argument, saying the cargo, which has remained in Turkish hands, belongs to Syria.
And while Russia has voiced concern about the planned deployment of NATO's Patriot air-defense missiles on Turkey's border with Syria, it has carefully balanced its statements on the subject, avoiding any sharp criticism of Turkey.
Ushakov said despite the disagreements on Syria, a candid exchange of views with Turkey will help "if not narrow the gap, at least understand each other's moves better."
Russia and Turkey have robust economic ties, which will be the main focus of the talks in Istanbul. Turkey is a top consumer of Russian natural gas, while Russia is a major market for Turkish construction companies. Ushakov said trade between the two countries, which totaled $32 billion last year, is expected to grow to $100 billion in the coming years.
Among other projects, Russia is building Turkey's first nuclear power plant.
Turkey is also a top travel destination for Russians, with more than 3.5 million Russian tourists visiting last year.
Putin had been expected to visit Turkey in October, but he postponed that and several other foreign trips, and spent most of the past two months at his suburban residence. He first showed signs of discomfort walking at a summit of Asia-Pacific leaders in Vladivostok in early September.
The business daily Vedomosti claimed Putin had injured his back shortly before the summit in a widely publicized flight in a motorized hang glider teaching Siberian cranes to migrate.
Putin's only air travel since then was a trip in early October to Ulyanovsk, a city 725 kilometers (450 miles) from Moscow.
His spokesman, Dmitry Peskov, has portrayed Putin as a robust athlete who pulled a muscle during judo training.
His chief of staff, Sergei Ivanov, said Friday that Putin had sustained a "light sports injury" and his busy travel schedule in December confirms he is in good health.
Putin plans to visit Turkmenistan on Wednesday and make other foreign trips before the end of the year.