premise: Malaysian bomb-maker Azahari Husin, who was tracked down and killed by police in November, as well as his on-the-run compatriot Noordin Mohammad Top, were both linked to the bombings and are believed to have spent time in Solo.
  Indonesia's intelligence agency warned last week that information indicated extremists may be planning attacks over the Christmas-New Year period in large cities across the sprawling archipelago.
  Jakarta police have said they will deploy 18,000 officers across the capital during that time.
  Nineteen people were killed when Islamic extremists launched a coordinated nationwide bombing campaign targeting churches and priests on Christmas Eve in 2000.
  The attacks were blamed on the Al Qaeda-linked Jemaah Islamiyah (JI) network, which has also been blamed for a string of deadly attacks in Indonesia since then, including the 2002 Bali bombing, which left 202 people dead.
   Why were Husin and Top tracked down and killed by Malaysian police?
hypothesis: information indicated extremists may be planning attacks