The pope intervened and overruled John, sparking a series of tit-for-tat exchanges that resulted in John's excommunication in 1209.

THE phoney war between BT and Mercury erupted in tit-for-tat exchanges yesterday.

The expulsion of diplomats was a weapon used regularly in the cold war when tit-for-tat exchanges were as common as genuine spy swaps.

Although the candidates on the trail scarcely mention each other and usually only when prodded at a news conference, aides have been engaged in daily tit-for-tat exchanges for weeks, largely through e-mail messages to reporters.

Dozens of people died in what appeared to be a tit-for-tat exchange between A.N.C. supporters and those still loyal to Mr. Nkabinde.

By attacking air defenses in four areas in southern Iraq, the United States hoped to pressure Mr. Hussein into withdrawing his forces from northern Iraq without entering a tit-for-tat exchange there.

So-called "tit-for-tat" exchanges have occurred, notably during the Cold War.

Perhaps television's role in all these tit-for-tat exchanges on blame and responsibility is being shortchanged.

This tit-for-tat exchange of adding a couple hundred yards here or there was left in the dust of the Australian outback in 2009 with the opening of Nullarbor Links.

"As their tit-for-tat exchanges escalate, for example, two children will often both assert that the other hit them harder."