DAMASCUS, Syria, Feb. 15 (UPI) -- Last week, Turkey began shelling Kurdish forces in northern Syria, while an agreement between world powers in Munich allowed Russia more time to help the Syrian military improve its bargaining position for upcoming talks in Geneva.
Faced with calls from France and the United States to stand down, Turkey said Sunday it would continue shelling Kurdish rebel forces on its border frontier with northern Syria.
Voice of America quoted Turkish Prime Minister Ahmet Davutoğlu as saying he would not allow the Kurdish People's Protection Units, or YPG, "to carry out aggressive acts."
On Saturday, the Turkish military began shelling Kurdish positions north of the city of Aleppo, where a Russian-backed Syrian military offensive is threatening encirclement.
Officials in Ankara said the move was in response to Kurdish rebels firing on Turkish troops. Davutoğlu had warned earlier that Turkey would attack if faced with a threat on its border -- much of which is controlled on the Syrian side by the YPG.
Artillery shells rained down on the countryside around the YPG-controlled border town of Azaz and the Menagh air base, which were captured last week from other rebel groups. Davutoğlu demanded the YPG withdraw from both locations.
Kurdish officials denounced the shelling and insisted the Menagh air base was being occupied by a Kurdish-allied Arab rebel cell known as Jaish al-Thuwwar. Both the YPG and Jaish al-Thuwwar are members of the Syrian Democratic Forces, a coalition of Kurdish, Arab and Assyrian rebel groups that, under cover of U.S.-led coalition airstrikes, has made gains against the Islamic State in northern and eastern Syria.
Pentagon spokesman John Kirby called on both Ankara and the YPG to exercise restraint and refocus efforts against IS fighters, while the Syrian government of President Bashar al-Assad characterized Turkey's actions as "direct support to armed terrorist organizations."
Turkey sees the YPG and its political arm, the Democratic Union Party, or PYD, as offshoots of the Kurdistan Workers' Party, or PKK, a Kurdish militant group that has sought autonomy for decades by waging an insurgency against Turkish security forces.
The United States and the European Union consider the PKK to be a terrorist group, and on Wednesday Turkish President Recep Tayyip Erdogan denounced the United States for its failure to recognize the PYD in the same light.
Amid the shelling Sunday, the YPG said it captured the village of Ayn Daqnah, east of Menagh and south of Azaz. On Tuesday, activists said the YPG occupied two villages in northern portions of the province at the request of local Arabs seeking refuge from Russian and Syrian airstrikes.
The Kurdish advances come amid complex multi-sided fighting in Aleppo province, where the Syrian military, so-called "moderate" Arab rebel groups, Islamic jihadists with IS and al-Qaida's Nusra Front, and the Kurds are all battling each other for supremacy.
In particular, pro-Assad forces -- with support from Russian airstrikes, Hezbollah fighters and Iranian advisers -- are fighting to cut off Aleppo City from supply lines leading to the Turkish border.
Turkey, which faces pressure to allow in tens of thousands of Syrian refugees gathered on its border, has criticized the United Nations for telling Ankara to let in asylum seekers while simultaneously failing to halt Russian airstrikes that led to the exodus from Aleppo.
Tensions have been high between Ankara and Moscow after Turkey downed a Russian fighter jet accused of violating Turkish air space last year. Turkish officials blame Russia for the refugee crisis on their border and have expressed chagrin over Russian airstrikes in support of Assad, whose regime they oppose. Moscow and Damascus accuse Turkey of supporting terrorist organizations by allowing militants to cross its southern border into Syria.
Activists say Turkey allowed hundreds of Syrian rebels to pass from Idlib province into Turkish territory and back into Syria's Aleppo province Sunday to defend the border town of Tal Rifat against the Syrian military.
Turkish officials on Saturday expressed willingness to launch a ground operation inside Syria alongside forces from Saudi Arabia -- which, along with the United Arab Emirates, offered earlier this month to supply troops, including special operations forces, for a U.S.-led coalition ground effort against IS in Syria.
The same day, Turkish Foreign Minister Mevlut Cavusoglu said Saudi Arabia was deploying military jets to Turkey's Incirlik Air Base to conduct anti-IS airstrikes alongside U.S. warplanes.
Meanwhile, the Syrian military has continued making steady gains since Russia's intervention on behalf of Assad last September.
On Sunday, Syria's state news agency, SANA, reported pro-Assad forces captured several villages in the northern countryside of Latakia province and the eastern countryside of Aleppo province, as well as several hills in the southeastern Homs province.
The Syrian Observatory for Human Rights, an activist group monitoring the conflict, said Saturday the Syrian military also was advancing through the Aleppo and Hama provinces toward the IS capital of Raqqa.
The gains came four days after an IS suicide bomber reportedly killed at least nine people at a police club in Damascus.
The complicated fray in Aleppo province raged on as foreign ministers from the 17-member International Syria Support Group met in Munich last week.
On Thursday, U.S. Secretary of State John Kerry and Russian Foreign Minister Sergei Lavrov announced a plan for a "cessation of hostilities" in Syria that would begin in a week's time, enabling humanitarian aid shipments to reach besieged areas. A formal cease-fire is anticipated to follow at a later date.
However, the Syrian opposition and the Damascus government were not present for the agreement, which some diplomats have said "might not be worth the paper it was written on."
Analysts say the scales have been tipped in Assad's favor after six months of Russian airstrikes, and any settlement under the current balance of power would benefit the Syrian government.
"Russia's agreement in Munich on Thursday to a temporary truce is predicated on a favorable configuration of forces inside Syria," BBC Middle East analyst Fawaz A. Gerges writes. "Freezing the battlefield lines would work in President Assad's favor."
Russia began its Syria air campaign under the auspice of fighting IS forces, but activists and Western leaders say most of Moscow's airstrikes have targeted moderate rebels opposed to Assad -- which Russia denies.
On Sunday, U.S. President Barack Obama spoke by phone with Russian President Vladimir Putin about the Munich agreement, asking Moscow to play "a constructive role by ceasing its air campaign against moderate opposition forces in Syria."
Russian airstrikes in January killed more than 470 Syrian civilians, including more than 120 children, according to SOHR. Russia has previously rejected such claims, insisting its pilots "never missed their targets."
On Thursday, the U.S. State Department dismissed allegations by Moscow that American military jets conducted airstrikes in Aleppo City the day prior, including against two hospitals. U.S. officials contended coalition warplanes were nowhere near Aleppo at the time.
Peace talks in Geneva between delegates from the Syrian opposition and Damascus fell apart earlier this month in the face of the Russian-backed offensive in Aleppo. U.N. officials hope to restart the talks by Feb. 25 -- and removing moderate rebel forces from the equation would strengthen Assad's bargaining position in Geneva, casting him as the only viable alternative to the IS threat.
"This, presumably, is why [Russian officials at the Munich conference] initially did not want any truce to start until 1 March, giving them a clear three weeks to achieve their military objectives in Syria," Gerges writes.
Still, some in the opposition have expressed optimism over the terms of the Munich agreement. The BBC quoted one delegate as saying, "If we see action and implementation on the ground, we will be soon in Geneva."
Turkey, meanwhile, is attempting to work against the Assad regime, defeat IS, stanch the flow of refugees and prevent the spread of Syrian Kurdish forces along its southern border.
The latter of those strategic objectives puts Turkey in a difficult position with its Western allies, especially the United States, which sees the Syrian Kurds as one of the few forces on the ground capable of delivering victories over IS.
As well, Ankara's announcement of a possible ground intervention alongside Saudi troops could dangerously escalate the Syrian conflict even further.
While Saudi Arabia and other Sunni Gulf states are concerned about the spreading threat of IS, they also see Syria as a proxy battle against the forces of Shia Islam -- specifically Iran. If Assad, who is a member of Syria's Shia-affiliated Alawite sect, is cemented to power, Syria could serve as a strategic foothold for Iranian military forces -- as well as the Tehran-backed militant group Hezbollah -- which are fighting on behalf of Assad.
Amid this complex morass comes shifting strategies and alliances.
The Kurdish population in the Middle East has long sought autonomy from its Arab neighbors and has added to Kurdish territories as it captures ground from IS. The United States has traditionally supported the Kurds, first in Iraq against the regime of Saddam Hussein, then against Sunni insurgents during the American occupation of the country, and now in both Iraq and Syria against IS.
However, Syria's Kurds may be entertaining extra support from Russia. On Wednesday, Kurdish officials presided over the opening of a representation office in Moscow.
"Russia is a great power and an important actor in the Middle East," Voice of America quoted Merab Shomoyev, chairman of the International Union of Kurdish Public Associations, as saying.
"It is, in fact, not only an actor, but also it writes the script," he said.
Analysts say the move doubles as a positive for Russia as well as the Kurds, who both share an enemy in Turkey, but they also note it is unlikely to negatively affect Kurdish relations with the United States, its primary ally.
More troubling to observers is the prospect that Western-backed moderate Arab rebel groups -- which are rapidly losing ground to the Russian-supported Syrian regime -- could turn to powerful jihadist organizations such as the Nusra Front or IS for a chance to gain back territory.