Everybody (including Mrs. Gandhi) knows what Yahya Khan does in a tight corner. He lashes out. He lashed out when Sheikh Mujibur Rahman tried to push him too far. He will, surely, resort to desperate force of arms if India’s tanks continue rolling across the strategic enclaves of East Bengal.

The difficulty - and potential tragedy - of the situation is simply that Mrs. Gandhi seems increasingly bent on provoking such a desperate fling. Her military incursions, observers agree, are not decisive strikes but calculated provocations: generalized pressure to a specific end. She seeks either the release of Mujib and an autonomous Bangladesh, or outright military victory.

But, dismayingly as the days of half-war slip by towards all-out conflict, India’s tactics look more and more fallible. They look, in fact, like a muddled amalgam of bureaucracy and brigade bluster - not calculation. They are disastrous diplomatically, for who now believes that Bengal is an internal Pakistani crisis with no Indian role in negotiations? They are disastrous politically, for Pakistan’s impending counterblow may seem a just response after so many taunts. They are disastrous psychologically, for Yahya will never free Mujib in circumstances involving such direct, crushing personal humiliation - and Bangladesh without Mujib will fall apart fast.

Nobody doubts for a moment that India acts under grave duress. Nine million refugees tend to dictate their own solutions. The Big Powers have done too little to help. But Mrs. Gandhi will find even this problem becoming secondary if her divisions begin messy, bloody advance over the densely populated paddy fields of East Pakistan. The trouble with supposedly surgical military actions is that they frequently tumble out of control; and the road to Dacca is jammed with pitiful human beings.

How can so vast a catastrophe be turned aside? Not, demonstrably, by polite notes from the Big Powers. They have already flooded in upon New Delhi and Islamabad without notable effect. The better course, certainly, is bringing real-politik to bear. What price India’s new Moscow pact if the Kremlin cannot exercise restraints? What price a block on arms aid to India? What chances of concerted UN action? The Security Council could move, even though there are bitter disputes on Bangladesh, because Mrs. Gandhi is haplessly swinging America, Russia, and China to the view that she must be stopped. This (which would freeze existing borders and despairingly gloss over matters like the refugees or democracy) would be bitterly resented in India - with some justice. But if wholesale devastation is the only alternative, rough injustice may appear the inevitable course. It is not a position from which Mrs. Gandhi can win. She should think again and start talking before Bangladesh cause - one of the strongest causes in the world - fritters away in pointless violence.