But recently, public outrage has increased the risks for terrorist groups claiming responsibility, making governments far more likely to retaliate with military strikes or economic sanctions against nations that sponsor attacks.

"The difference between American hackers and Chinese hackers is that the Chinese government has a pretty good history of sponsoring attacks using surrogates."

India routinely blames Pakistan for sponsoring such attacks, charges that Islamabad routinely denies.

It may be that Chinese hackers are not sophisticated enough to hide their tracks better but any country sponsoring attacks has an incentive to disguise that fact.

If he has sponsored terrorism and attacks on US soldiers in Iraq, why don't they arrest him?

In a now entrenched dynamic, India blamed Pakistan for sponsoring such attacks, while Pakistan said India's oppression of its Muslim minority fueled the violence.

Saddam Hussein threatened that it was in his power to sponsor terrorist attacks on the countries ranged against him.

He used to sponsor terrorist attacks until the then President Regan gave him a taste of his own medicine.

Some officials, though, did blame Pakistan, which India has accused of sponsoring frequent attacks by Islamic militants seeking to wrest control of the Kashmir Valley.

A senior Israeli security official said that through Hezbollah, Syria was sponsoring Palestinian terrorist attacks against Israel.