BY any normal standard, the firing of 250 rounds of tear-gas and the deployment of some 1,250 heavily armed police and Correctional Services Department (CSD) personnel to shift a group of peaceful demonstrators barricaded into one section of a well-guarded detention centre amounts to an excessive use of force. The number of officers and the amount of equipment used in yesterday's operation at the Whitehead detention centre, may have been justified, as CSD chief Eric McCosh claimed, to guard against an attack from other sections of the camp. But population movements from camp to camp have been carried out in the past without similar levels of force. Moreover, 250 rounds of CS gas is more than was unleashed in any of the worst of the camp riots of 1989 and 1990. Again, it may have been true, as Mr McCosh argued, that tear-smoke was the ''minimum degree of force'' required to get people off the roof. However, the quantity was out of proportion to the situation. But this was not an operation planned according to normal standards. It was the opening battle in what is clearly intended to be a long war to get the last 26,000 boat people out of the camps and back to Vietnam. If this hard core does not ''volunteer'' - a curious euphemism in the face of such intimidation - then they will be repatriated against their will. Logically, it makes no sense to make further threats of further shifts of camp and forcible repatriation if they do not volunteer, when they could be put directly on to an ''orderly repatriation'' flight tomorrow with no more questions asked. But in the war of nerves the authorities have now decided to fight - with no holds barred - similar acts of disruption and disorientation return the initiative to the Government. What yesterday's tactics suggest is that the Government feared it had lost control. The resistance in Section Seven was organised like a military campaign. Inmates were blocking the gates, conducting drills in the middle of the night, manufacturing weapons - fortunately relatively few - and making gas-masks ready for invasion. Clearing the camps of those people who have failed the test of refugee status is justified: Hong Kong has no special obligation to people who really are illegal immigrants. But the problem in waging a form of war against them is - as in all wars - the civilian victims. More than two-thirds of the resisters flushed out with gas and loaded onto vans yesterday were women and children under 16. The 57 gas-masks seized during the operation would not have helped them. Seizing back the initiative is a poor excuse for such heavy-handed behaviour.