Americans watched this week as U.S. interests abroad became targets of Muslims enraged over a film mocking their religion. It was a storyline featuring familiar characters in the so-called war on terror, but some experts say the narrative may be overplayed.

Though radical Islam and Western interests are commonly the primary subjects of stateside conversation when it comes to terror, domestic terrorists pose significant threats to the homeland, experts say, and the U.S. needs to do more to safeguard itself from the threat within.

A handful of recent events -- including the deadly rampages at a Sikh temple in Wisconsin and an Aurora, Colorado, theater -- have left communities in grief and raised additional questions about whether we're paying enough attention to domestic terrorism following the September 11, 2001 attacks.

"9/11 has set the threshold for what terrorism is in the minds of many Americans, and if domestic terrorism lacks the magnitude, it must not be terrorism," said Daryl Johnson, a former counterterrorism expert at the Department of Homeland Security. Johnson says he left DHS in 2010 out of frustration.

According to Johnson, many in the government have taken a myopic view based on the severity and magnitude of 9/11, leaving them unable to move beyond the threat posed by jihadist groups.

Heidi Beirich, director of the intelligence project at the Southern Poverty Law Center, a civil rights group, claims the domestic threat cannot be overlooked after the shootings at the Sikh temple.

"Domestic terrorism is as much a threat as foreign terrorism. The government needs to get serious about this," she said.

While the feds have said that the Aurora incident was not a terrorist act and the FBI continues to investigate whether the shooting at the Sikh temple was an act of domestic terrorism, these incidents have drawn attention to domestic threats.

The FBI's shorthand definition of domestic terrorism is "Americans attacking Americans based on U.S.-based extremist ideologies."

Far right domestic terrorism on par with foreign threat, experts say

According to a May 2012 congressional research service report, counterterrorism efforts have been shaped largely in response to acts of foreign terrorism. The emphasis of counterterrorism policy since 9/11 has been on jihadist terrorism, despite the fact that domestic terrorists have been responsible for more than two-dozen incidents since 9/11, the report states.

The congressional report points to data collected by the National Counterterrorism Center's Worldwide Incidents Tracking System, which publicly lists 35 terrorist incidents occurring in the United States between the beginning of 2004 and September 2011. Of those, 25 were linked to domestic terrorists.

Experts say the domestic threat can no longer be pushed to the background.

A September 2011 survey by the New America Foundation and Syracuse University's Maxwell School of Public Policy examined 114 cases of non-jihadist terrorist acts in the 10 years following 9/11. In comparison, they found 188 cases of Islamist terrorism in the U.S. for the same period. Some of the cases examined involved plots that were foiled and unsuccessful.

Examples of domestic terror cases since 9/11 include a 2001 plot by Earl Krugel, a member of the Jewish Defense League, to blow up the office of Arab-American congressman Darrell Issa and the King Fahd mosque in Culver City, California and the February 2010 suicide attack by Andrew Joseph Stack III, where he flew his airplane into the IRS building in Austin, Texas killing one other person and injuring many more.

According to the survey, the 114 cases of domestic terrorism do not represent a complete survey of non-Islamist terrorist cases. Keeping track of domestic terrorism incidents is far more difficult than tracking incidents of jihadist terrorism. Jihadist terror cases are nearly all tried under anti-terrorism laws or statutes dealing with "material support" to terrorist groups. Domestic terrorism cases on the other hand are often tried under an array of other statutes, from weapons and explosives violations, property destruction and arson to "seditious conspiracy," the survey stated.

These ideologies behind the domestic attacks encompass a wide range of groups. On the left, you have anarchists and some Communist factions. On the right, there are white supremacists and sovereign citizens, participants of which do not recognize U.S. currency, taxation or city, state or federal laws. There are also more single-minded groups that include some animal rights, environmental and anti-abortion outfits.

While left-wing groups have frequently vandalized property and committed arson, right-wing groups present a more deadly threat given their affinity for hoarding weapons and explosives, according to Johnson, who now runs a private security consulting firm.

"What worries me is the fact that our country is under attack from within, from our own radical citizenry," Johnson said. "Yet our leaders don't appear too concerned about this. So, my greatest fear is that domestic extremists in this country will somehow become emboldened to the point of carrying out a mass-casualty attack because they perceive that no one is being vigilant about the threat from within."

Despite the threat right-wing groups pose, intelligence-collection efforts have not received the same attention as foreign threats, according to the congressional report.

The Southern Poverty Law Center has documented a dramatic growth in the number of militias and hate groups operating in the U.S. over the past decade. Currently, there are more than 1,000 hate groups in the United States, according to the center, which says it was monitoring the alleged Sikh temple gunman for years before the attack.

"They are like little sitting time bombs," Johnson said.

In the aftermath of the Wisconsin shooting, online forums among radical right-wing hate groups have ignited with vitriolic messages.

"Take your dead and go back to India and dump their ashes in the Ganges, Sikhs," Alex Linder, a neo-Nazi who operates the racist website Vanguard News Network, wrote on his forum. "You don't belong here in the country my ancestors fought to found, and deeded to me and mine, their posterity. Even if you came here legally, and even if you haven't done anything wrong personally. Go home, Sikhs. Go home to India where you belong. This is not your country, it belongs to white men."

According to Johnson, there are certain poisonous belief systems in this country that have a history of violence.