Tens of thousands of extra armed police are being deployed across Muslim Indonesia today to protect Christians who wish to celebrate Christmas Mass tonight and tomorrow, Christmas Day, amid fears of religious violence. With the memory of terrorist attacks last Christmas Eve still fresh for many, the police are being deployed at churches across the country. The United States Embassy has warned its citizens of 'indications' that similar violence may occur again this year. The embassy issued a statement warning Americans to exercise vigilance. A year ago today, bombs ripped through churches in Jakarta and across the archipelago, killing 19 people, injuring many more, and showing up Jakarta's security and judicial officials yet again. No one has been caught or prosecuted for last year's bombs. Popular theories are that it was the work of militant Islamists or other thugs paid by old-guard power brokers such as Hutomo 'Tommy' Mandala Putra, former president Suharto's youngest son. 'Prevention is always a good idea, even if this Government has no idea about a cure. At least all these cops might make a potential bomber think twice, even though we all know there's no guarantee of safety,' said one Jakarta resident who plans to worship as usual. Police spokesman Saleh Saaf said: 'Tens of thousands of police will be assigned on Christmas Eve and extra security will be given to churches in places deemed as conflict areas.' In Jakarta alone, 15,000 police will guard hundreds of churches. Jakarta deputy police spokesman Alex Mandalika said police will 'selectively screen' worshippers attending services on Christmas Eve and Christmas Day. 'Personnel will work together with church officials and they will alert us to the presence of unknown parishioners and we will search their bags,' Mr Mandalika said. In a statement, the United States Embassy 'reminds all Americans in Indonesia of the events of Christmas Eve 2000, when bombs exploded at churches in a number of cities throughout Indonesia'. Explosions occurred or unexploded devices were found in Jakarta, Surabaya, Medan, Pekanbaru, Batam, Bandung, Sukabumi, Mojokerto, and Mataram. 'There was no evidence that American citizens or interests were targeted. However, there are indications that similar incidents could occur again this year,' the statement warned. 'American citizens are urged to be extremely cautious during the coming days. 'They should maintain a high level of vigilance and take appropriate steps to reduce their vulnerability. 'Americans should maintain a low profile, vary routes and times for all required travel, and treat mail and packages from unfamiliar sources with suspicion,' the embassy warned. Last year's bombing campaign was partly attributed to a desire to discredit and depose then president Abdurrahman Wahid, and so could be seen as successful. But analysts add that such attacks appear designed to discredit Indonesia's more open society as a whole, depriving the current Government of immunity. Renewed fighting between Muslims and Christians has occurred in Central Sulawesi and in the Maluku capital of Ambon in recent weeks. Last week, Muslim gunmen shot at a Christian-owned speedboat taking women with their produce to market in Ambon, killing nine of the 11 on board. Police and the army have failed to establish their own neutrality in such conflicts and the central Government continues to ignore the sources of tension which lie more in economics and injustice than religious rivalry alone. Continued government tolerance of the militant Laskar Jihad organisation of Muslim fighters is also said to be part of problem.