ANKARA, March 23 (Xinhua) -- Hurdles remain amid Turkey and Russia's pledge of healing rift and boosting bilateral ties, as both sides still have problems with issues over Syrian and bilateral trade.

Russian charge d'affairs in Turkey was summoned on Thursday, as row spiraled after a Turkish soldier was killed by sniper attack from the Syrian border, where the Kurdish Syrian Democratic Union Party (PYD) elements are in control, and the Russian military elements were recently deployed.

Russian President Vladimir Putin and Turkish President Recep Tayyip Erdogan met in Moscow in early March for the resumption of Russian-Turkish High Level Cooperation Council since the relations were suspended after Turkey downed a Russian warplane in 2015.

The airspace violation problem, which stemmed from the jet downing incident, is also a sign of wide discrepancy in dealing with Syrian crisis.

The icy Turkish-Russian ties began to thaw in June, 2016 when Erdogan wrote a letter to Putin to express his deep sorrow over the jet incident.

Ankara and Moscow have long been at odds over the conflict in Syria, where Russia supports President Bashar al-Assad and Turkey backs rebel factions fighting to topple the Syrian regime.

Ankara recently tuned down its objection against Assad and brokered a ceasefire deal with Russia using its leverage on Syrian rebel groups. However, the differences over Syria, particularly on military cooperation with the Kurdish militia, kept the relations strained.

Russia keeps up its cooperation with Syrian Kurdish militia, in an effort to balance U.S. military infrastructure in northeast Syria, in collaboration with People's Protection Units (YPG) armed wing of the PYG, which Ankara sees as an offshoot of outlawed Kurdistan Workers' Party.

Kurdish militia forces have carved out three autonomous cantons along Turkey's border since Syria was plunged into chaos in March 2011. Turkey is particularly concerned that the emergence of an autonomous or independent Kurdish entity in northern Syria may set a precedent for its own Kurds and encourage Kurdish separatism at home.

Turkey launched Operation Euphrates Shield into Syria in August, 2016 to push Islamic State (IS) away from its border and prevent efforts by Syrian Kurds to connect two cantons of control in Syria's north.

Despite constant warnings of Ankara, Russia has deployed military elements this week in northwestern region of Afrin that is controlled by the Kurdish militia. The YPG spokesperson stated that Russia is setting up a military base in agreement with the Syrian Kurdish armed group and will train fighters.

However, in a statement put out shortly after the YPG statement, the Russian Defense Ministry said there were "no plans" to create additional military bases in Syrian territory, but added that a "reconciliation center" for prevention of ceasefire violations were established as part of a truce deal brokered by Turkey and Russia on Dec. 30, 2016.

Turkish Foreign Ministry Spokesperson Huseyin Muftuoglu said that coordination is needed between Turkey and Russia, which are the guarantor countries of the ceasefire, adding that Russia has not informed Turkey about its military deployment.

Moreover, lifting the embargo on Turkish products export has been among the top objectives for Ankara during the bilateral meetings.

Russia removed its restrictions on tourism agencies for travel to Turkey and resumed charter flights so that Turkish government will benefit tourism profits. Yet, sanctions on export of some Turkish agricultural products remain overwhelmingly in place, including tomatoes, apples, strawberries, zucchinis, pumpkins and most poultry products.

Moscow also delays the process of easing its visa regime at least for service passports holders and businessmen.

As Turkey's constant calls for lifting restrictions are not met, Turkey recently excluded Russia from import licenses issued for a list of accepted tax-free origins, putting on hold purchases of Russian wheat, corn and sunflower oil.

Turkey is the second largest Russian wheat importer and one of the largest markets for Russian corn and sunflower oil.

Russian Deputy Prime Minister Arkady Dvorkovich told Turkish Deputy Prime Minister Mehmet Simsek on the phone Wednesday that the move is hindering restoration of ties between the two countries.