Sen. Joseph Lieberman, I-Conn., is right to abandon political correctness in his desire to know what effect, if any, Islamic terrorists had on the man accused of killing 13 people and wounding 29 others at Fort Hood, Texas.

Lieberman is seeking an investigation of links between the accused killer, Maj. Nidal Malik Hasan, and Islamic radicals.

On the other hand, some national leaders are taking the approach that we should conclude quickly that Hasan was motivated solely by his own mental illness. Our nation's tradition of religious tolerance argues against accusing other Muslims of influencing Hasan, they say.

That is not entirely true. Many Muslim leaders have condemned Hasan's actions. A few have praised him.

The American tradition of tolerance does not extend to religious leaders who advocate needless violence.

Lieberman is right to insist that more needs to be known about whether Hasan was influenced by Muslim radicals.