On the anniversary of the 9/11 attacks, we are well served to assess the threat of extremism and hatred in America today. As we do so, we discover that the picture is far from rosy, and that there is ample reason for concern. Still the picture is not all dark clouds.

Various reports document an overall increase in ideologically motivated violence in the United States. These incidents have included:

• The shooting by a longtime white supremacist and anti-Semite at the U.S. Holocaust Memorial Museum in June.
• Also in June, the shooting death of one, and wounding of another, uniformed American soldier in Little Rock, Ark., by an American Muslim convert who had searched the Internet for Jewish institutions and other potential targets.
• The shooting death in June of an abortion-services provider in Kansas by an antiabortion extremist who was also active in the antigovernment extremist movement.

While these perpetrators did not belong to specific hate groups, they appeared to be motivated by their own radical ideologies. These and other extremists are also influenced by current events, including the economic crisis, the wars in Afghanistan and Iraq, the immigration debate, and the election of Barack Obama as the first African American president. In recent months, antigovernment movements have been growing in size and activity as well. These movements, as well as the white supremacist movement as a whole, have demonstrated growing levels of anger, intensity and agitation.

Anti-immigrant sentiment has taken on a new poignancy recently with the dramatic growth of the immigrant population. There has been divisive rhetoric and controversial legislation in Hazleton, Pa. Further west, in Shenandoah, the murder of a Mexican immigrant, widely considered a hate crime, received national attention.

Political discourse has achieved new lows, and the mean-spirited commentary, demonization, and conspiratorial tones of some political leaders have been mirrored and amplified by a number of talk-show personalities. Blatantly or obliquely, they have pandered to fears, distorted truth, and at times scapegoated minorities.

So, in the face of these realities, do we despair? No.

First, security and vigilance remain vital. Assiduous police work thwarted an attempted assassination by neo-Nazi skinheads of the president. Law enforcement consistently monitors national developments and alerts local agencies to take necessary precautions. They remain current with extremists' methodologies; for example, the use of electronic communications to recruit and spread propaganda, organize, and obtain funding and other resources.

Second, our leaders must stand up to expressions of hate, intolerance, and appeals to division and ignorance, and challenge us to do the same. While not frequently enough, we have seen law enforcement, campus, clergy, and elected officials do this.

Our schools have a stake in helping our students be mindful of the threats posed by hate mongers. Programs to foster respect for difference and allow students to serve as role models and peer leaders are to be taken seriously. Close to 200 schools in Pennsylvania are attempting to do this by participating in the Anti-Defamation League's No Place for Hate program.

Finally, we need to look beyond ourselves, as well as within, to understand and be compassionate toward others, and to allay their fears of isolation and victimization. Otherwise, tensions grow and alienate one group from the other, detract from faith in our government, and tear at the fabric of our society.

As we pause to remember the horrors of eight years ago, we recognize that there are abundant challenges posed by extremism and hatred. These challenges will test our mettle and our resilience. They will also test our commitment to our core and shared values: respect for others and their rights, and the preservation of our democratic principles and traditions. As we remember the tragedy of Sept. 11 and are sobered by the work before us, we should recommit ourselves to meet these challenges.