Turkey may face a heightened campaign of such attacks. The bombings may also poison an already volatile political atmosphere and further inflame relations between the state and Turkey's Kurdish groups, some of which were prominently involved in the Ankara rally.
Much will depend on where blame is laid, which will influence the response of the Turkish authorities and political opposition, especially the Kurdish parties.
Whoever chose Saturday's rally in Ankara as a target wants to stoke polarization and violence in Turkey -- and destroy an already fragile political dialogue.
ISIS brings its war to the Turkish heartland?
The bombings Saturday certainly bear the hallmarks of ISIS, which has threatened to attack Turkey since the government agreed to join the international coalition against the group.
In its online magazine Dabiq, ISIS said of Turkey last month that "this government and army is one of blatant apostasy." In a video released in July, an ISIS supporter urged Turks to "conquer Istanbul, which the traitor (Turkish President Recep Tayyip) Erdogan works day and night to hand over to crusaders."
But Turkish Prime Minister Ahmet Davutoglu said Saturday that besides ISIS, the "PKK and far-left group DHKP-C are all potential suspects."
The PKK is the Kurdistan Workers' Party, a militant group that has waged a separatist campaign for more than 30 years. The DHKP-C, or Revolutionary People's Lieration Party-Front, is a far-left group that claimed responsibility for a 2013 suicide bombing at the U.S. Embassy in Ankara.
It would have been a brutally cynical act for the PKK to attack a pro-peace rally attended by Kurds. But Davutoglu asserted that in recent days many suicide bombers were arrested after crossing from northern Iraq. If so, that could implicate the PKK, which has bases there, rather than ISIS, which does not control any part of Iraq's border with Turkey (though it does have access to parts of Syria's border with Turkey).
Daniel Nisman, chief executive of the Levantine Group, which studies the eastern Mediterranean, believes the size and co-ordination of the blasts points to ISIS. He told CNN that ISIS targets minorities, such as the Shia in Saudi Arabia, to fuel sectarian tensions and because they tend to be softer targets.
The Suruc bombing quickly led to the collapse of a truce between the Turkish government and the PKK. Kurdish leaders blamed the authorities for negligence in allowing ISIS to target them. The PKK went further: After killing two Turkish police officers, it openly accused the Turkish security forces of collaborating with ISIS.
A renewed cycle of violence between the security forces and the PKK has since cost hundreds of lives. It's in ISIS' interest to stoke this violence, as it weakens their Kurdish enemy and keeps the Turkish army and air force occupied. In northern Syria (and especially Hasakah province), ISIS is under pressure from the Kurdish YPG fighting force
, which has close ties to the PKK.
Until now, says Nisman, the Turkish government and ISIS have seen Kurdish nationalists as the "greater enemy" and have been less concerned about each other. ISIS has so far been careful, for example, not to attack a rally of the ruling party in Turkey.
Nisman told CNN that the Turkish security forces have historically been competent in securing major cities and the border areas. But ISIS has established a deep presence in Turkey in the past two years. One counterterrorism analyst told CNN it uses certain neighborhoods of Istanbul as a financial hub.
Despite scores of arrests of alleged ISIS suspects in Turkey -- the latest batch was last week -- security analysts say it is virtually impossible to stop all ISIS activity on Turkish soil.
Erdogan said Saturday that "the solidarity and determination we are going to display in the face of this attack will be the biggest and the most meaningful response to the terror."
But solidarity has been in short supply in Turkey, with a combustible atmosphere ahead of critical national elections November 1
. Distrust is rampant.
The vote next month will be Turkey's second general election this year. Erdogan wants to regain a parliamentary majority for his Justice and Development Party (AKP). In so doing, he's appealed to nationalist sentiment in Turkey -- which tends to be strongly anti-Kurdish.
Analysts don't expect Erdogan's party to win an outright majority in November, leading to perhaps another unstable coalition.
The last election left the main Kurdish party, the HDP, with an important role in the national parliament. The next few weeks may be crucial in deciding whether Turkey's Kurdish minority embraces the political process or feels excluded from it.
Nisman and others say there are several critical factors in the days ahead.
- Hours after the Ankara bombings, the PKK said fighters were ordered to halt operations in Turkey unless they faced attack. Will the group hold to this renewed ceasefire, after more than two months of conflict with the Turkish army?
- Will the government show similar restraint if there are provocations by Kurdish extremists beyond the control of the PKK leadership? The prime minister's declaration of three days of national mourning is seen as a conciliatory gesture.
- Nisman points out that voter support for the Justice and Development Party is historically linked to the strength of the Turkish lira and financial markets. Renewed fighting with the PKK could damage both, and that may encourage government discretion.
- How will the Kurdish nationalist party, the HDP, respond to Saturday's bombings? Its leader, Selahattin Demirtas, called the Ankara bombings a "vicious, barbarous attack" -- but whom will the HDP blame?
Some furious Kurds at the scene of the attack blamed the AKP for orchestrating recent bombings and attacked a police car. Demirtas said he would refuse to take a call of condolence from Erdogan and has accused the authorities of failing to investigate previous attacks.
Five years ago, many of the metrics in Turkey looked much more positive. Its economic model was successful and growth healthy; its politics were stable as Erdogan's party enjoyed a comfortable parliamentary majority.
As prime minister (he became president last year), Erdogan's model for combining Islam and democracy appealed to many in countries emerging from the Arab Spring, such as Egypt, Libya and Tunisia. He was feted in all three countries.
Since then, Turkey has been flooded by as many as 2 million refugees as its neighbour Syria has imploded. Erdogan says the state has spent more than $7.5 billion caring for the refugees, and some analysts predict another 500,000 Syrians may seek shelter in Turkey.
"Turkey's resources and public patience are wearing thin," especially in the absence of international support, says a new report from The Brookings Institution.
The Turkish government has been pressing for the creation of a safe haven in northern Syria, guaranteed by a no-fly zone. But Russia's sudden intervention in Syria
has made that much less likely.
There are tensions between Turkey and Europe -- and between Turkey and the Gulf states -- about the process for removing Syrian President Bashar al-Assad.
Human rights groups have attacked what they call an increasingly intolerant and violent attitude toward dissent
And in the words of Hugh Pope of the International Crisis Group, peace between Turks and Kurds has been as elusive as ever.
"Each time they miss the chance to make peace, the terms of the peace deal change and become more difficult," Pope says.
The indicators look none too optimistic. The toxic combination would include a stuttering economy, renewed Kurdish unrest and an ISIS terrorist campaign in Turkish cities.
The shock of the Ankara attack might yet lead to a reappraisal by the government and Turkey's Kurdish minority.