TOKYO, Sept 17 (Reuters) - Six years ago on a Monday morning in March, members of a Japanese doomsday cult placed five plastic bags containing the deadly nerve gas sarin on crowded Tokyo subway trains, releasing the gas as the cars neared a station beneath the heart of the nation's government offices.
Within minutes of the attack by the Aum Supreme Truth cult, passengers began collapsing. Twelve people died and nearly 6,000 were left ill.
Now, in the wake of last week's shocking attacks by suicide pilots on U.S. power centres, some U.S. lawmakers and experts have upgraded their warnings that the future may hold far more chilling assaults involving chemical or biologicial weapons.
"For several years now, the U.S. government and Defense Department has identified as a major, serious threat the proliferation of mass destruction weapons including biological and chemical weapons," said Carl Thayer, a regional expert at the Asia Pacific Center for Security in Hawaii.
"The sarin attack has been used as an example of how this might be mounted," Thayer said. "It was the technical incompetence of those people who mounted the attack that limited the number of deaths.
"Determined terrorist groups will alter their tactics, so the likelihood has probably intensified," he said, adding that the threat would be magnified if U.S. retaliation killed large numbers of civilians.
Some experts have cautioned against exaggerating the threat, noting significant technical barriers exist to carrying out an effective biological attack.
But others, dubbing biological weapons in particular "the poor man's atom bomb," have urged increased efforts to counter any such assault.
HOW WIDESPREAD?
At the weekend, U.S. lawmakers again sounded the alarm and warned that the United States was ill-prepared to cope.
"In my judgment, it's not a question of if there will be biological or chemical weapons attacks, but when -- and of what magnitude," U.S. Rep. Christopher Shays, a Republican who heads the House government reform subcommittee on national security, said on Saturday in Washington.
An article in Jane's Intelligence Review earlier this month by Rand corporation expert Dr Peter Chalk said concerns about biological warfare and bio-terrorism had spread over the past decade due to several factors, including revelations as to the scope of Iraq's bio-warfare efforts after the Gulf War.
He estimated that the capability to produce biological weapons had spread to at least 17 states and cited indications that "sub-state terrorist organisations, including Osama bin Laden's Al-Qaeda, have an active interest in developing BT (bio-terrorism) capability."
U.S. officials have named Saudi-born Muslim militant bin Laden as the key suspect in last week's attacks.
JAPAN JOLT
The 1995 sarin attack could have been expected to jolt Japan into better readiness for chemical or biological attacks, but experts said Japan was still among the least-prepared, a legacy of its World War Two experiments with biological weapons.
"In general the capacity to cope is very limited," said defence expert Tomohisa Sakanaka. "It has been thought that even for the military even to do research on such things (as biological warfare) is itself dangerous."
Japan's military has had a chemical warfare unit, which now numbers about 130 personnel, since the Cold War days.
But it has shied away from developing anti-biological warfare capabilities because of fears of a backlash from its Asian neighbours, who still remember its top-secret Unit 731, which conducted biological experiments on Chinese, Korean and Russian prisoners of war during World War Two.
"We have learned too much from history," Sakanaka said.
Japan got a second wake up call in 1999 -- one year after North Korea test-fired a ballistic missile that passed over Japan -- when the United States alerted it to Pyongyang's biological and chemical weapons programmes.
Two years later, little progress appears to have been made.
A Defence Ministry spokesman said the ministry last year sought input from experts on what steps it should take and had sent officers to the United States to study ways to detect and protect against biological weapons.
This year the ministry is seeking a 2.9 billion yen ($24.62 million) budget to begin research on the topic of biological weapons and fund training in the United States.
00:50 09-18-01
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