(CNN) — British Prime Minister David Cameron says he will not call a Parliamentary vote on ISIS strikes unless he is sure of a clear majority in favor. “We will not hand a publicity coup to ISIL,” he said Thursday, using another name for ISIS.

The prime minister argued in Parliament for strikes on ISIS in Syria, saying, “The reason for acting is the very direct threat that ISIL poses to our country and our way of life.”

French authorities working to dismantle the network of terrorists behind the Paris attacks say another attack could have been just hours away when police closed in on the suspects’ hideaway last week.

Suspected ringleader Abdelhamid Abaaoud and another man were planning a suicide attack on the Paris financial district of La Defense on November 18 or 19, Paris prosecutor Francois Molins said Tuesday. But both men were killed during a raid in Saint-Denis, that caused the collapse of an entire floor of an apartment building.

The prosecutor did not elaborate on why authorities believed another plot was in the works.

And as Wednesday dawned, several other key questions remain unanswered:

– Where is the suspect Salah Abdeslam?

– Did a suicide vest investigators found in a Paris suburb this week belong to him? Was it intended for another attack?

– Who is the man who was killed after he detonated a suicide vest during the Saint-Denis raid last Wednesday? Was he involved in the Paris attacks?

Here’s a look at some of the threads authorities are following as they investigate the attacks:

The suspects on the run
It has been more than a week since an international arrest warrant was issued for Abdeslam.

Investigators haven’t detailed what they believe his role was in the coordinated series of attacks, but Molins said Abdeslam may have dropped the suicide bombers off at the Stade de France, then made his way to another Paris neighborhood. His fingerprints, Molins said, were found in a car connected with the attacks.

Belgium, and specifically a Brussels suburb with a history of links to terrorism, have been a focus of the investigation. Brussels, which has been under partial lockdown since Friday night, is to remain at the highest terror alert level until at least the start of next week.
But much of the metro was reopened on Wednesday, though two lines of the transport system remained closed.

Sources in France close to the investigation believe Abdeslam could not have survived so long on the run without help, and that might involve a support network in Belgium. They say extensive raids in Belgium on Sunday and Monday, when 21 people were detained, targeted people suspected helping organize the attacks.

Belgian authorities released the name and photo of another suspect wanted in connection with the Paris attacks. Police said Mohamed Abrini was driving another car that was abandoned in the Paris neighborhood where one of the November 13 shootings occurred. They said he had dropped off one of the bombers who attacked the Stade de France.

The suicide vest
A suicide vest found in a garbage bin could give investigators new clues about Abdeslam’s whereabouts and his possible role in the attacks.

Investigators are analyzing the vest, which was found in the Paris suburb of Montrouge, near where Abdeslam’s cell phone was traced on the night of the attacks, Molins said.

CNN affiliate BFMTV reported that the vest contained bolts and TATP, the same explosive as the suicide belts used by the Paris attackers.

Questions have been raised over whether Abdeslam aborted part of the attacks before fleeing toward Belgium. The Paris prosecutor suggested that could have been the case, noting that an ISIS message claiming responsibility for the attacks mentioned the 18th arrondissement, a Paris neighborhood where no attack occurred.

“Our investigation on that is still ongoing, to determine if Salah was planning on a suicide attack in the 18th arrondissement and why it didn’t happen,” Molins said.

But CNN terrorism analyst Paul Cruickshank aked why, if the suicide vest belonged to Abdeslam, would it have been discovered 10 days after the attacks? And if it doesn’t belong to him, then whose is it?

“It is possible that somebody else may have jettisoned it, an attacker that we don’t know much about at this point,” Cruickshank said. “So they’ll be doing all sorts of forensics, trying to establish who this belonged to, and that will be a huge priority for French investigators.”

Local authorities in Montrouge said garbage cans in the area are emptied “once or twice a week,” Le Monde reported.

The global battle against ISIS
French President Francois Hollande is in the midst of a week of diplomacy aimed at building a global coalition to fight ISIS in Syria and Iraq.

Hollande will hold talks Wednesday with German Chancellor Angela Merkel and travel to Moscow to see Russian President Vladimir Putin on Thursday. He hosted British Prime Minister David Cameron in Paris on Monday and met Tuesday with U.S. President Barack Obama in Washington.

France and Britain are already part of a U.S.-led coalition that has been bombing ISIS targets. Russia is conducting separate airstrikes against ISIS and other groups in coordination with the forces of Syrian President Bashar al-Assad.

Any efforts to form an alliance that includes both Russia and the United States are likely to run into thorny issues like Assad’s future role in Syria and international sanctions against Moscow for its interference in Ukraine.

Hollande has vowed to intensify the aerial campaign against ISIS, and the French military began Monday to use the aircraft carrier Charles de Gaulle in the eastern Mediterranean to launch strikes.

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