Turkish F-16 Shoots Down Russian Fighter Jet Allegedly Invading Turkish Airspace

"Terrorists' Accomplices" were the words Putin used to describe the Turkish government after a Turkish F-16 shot down a Russian fighter jet, claiming that the Russian plane was invading Turkish airspace. Although from an outsiders perspective it may seem that this random attack on a Russian fighter jet was in fact an act of terrorism on Turkey's part, the NATO ally's actions in regards to ISIL and the Syrian refugee crisis suggest otherwise.

The Russian fighter jet plummeting to the ground after being shot down

The Turkish government is credited with accepting the flow of over 2 million Syrian refugees in to their country, and spending more than 7 billion dollars to care for them. Contrastingly, a slew of American policy makers, terrorism experts, and Turkish watchers have observed Turkey's unwillingness to intervene and combat the extremism in Syria, despite their unquestioned ability to do so; Turkey's most recent actions (title) contribute to the rising suspicions of onlooking nations.
Turkey's actions, or lack thereof, put it's NATO allies in an awkward position of obligated support and assumption about the nation's motives. To add to this, the Turkish government's rocky history with Assad, combined with its unwillingness to shut down supply lines leading in to an ISIS-controlled territory, and it's overall ambivalence in regards to the Obama administration's anti-ISIL strategy since 2014 all contribute to a growing suspicion over Turkey's true motives in the fight to dissolve the Islamic State and the destruction it causes.
Presently, Turkey continues to send mixed messages to it's allies in regards to where it's support lies. Recently, a policy was implemented that would open up Turkish airbases to anti-ISIL forces to conduct combat operations with Turkey's pledged help, but so far the Turkish have reportedly spent the majority of their time combatting internal terrorist organizations that they have been fighting since the mid-1980s.
At the moment, few advisors in Washington believe Turkey has been or will be part of the solution in Syria, but the accommodating manner in which they are treating Turkish president Erdogan stems solely from a fear of losing access to Turkish territory.

Questions:
Based on the information above, and perhaps prior knowledge, do you think Turkey hold ulterior motives in the fight against ISIS? Why or why not?
Do you think that Turkey's past history with Assad (i.e. Assad's "betrayal" of the Turkish government in Syria) is the root of these motives?
Assuming that Turkey does have motives that conflict with those of it's NATO allies, what action should be taken?

Sources:
- http://www.politico.com/magazine/story/2015/11/isil-strategy-turkey-213392?o=0
- http://www.jamaicaobserver.com/assets/12411313/Russia-jet_w210.jpg
- http://www.theguardian.com/world/live/2015/nov/24/russian-jet-downed-by-turkish-planes-near-syrian-border-live-updates