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Pardeep Kaleka spent several days after 9/11 at his father's South Milwaukee gas station, fearing that his family would be targeted by people who assumed they were Muslim. No, Kaleka explained on behalf of his father, who wore a turban and beard and spoke only in broken English, the family was Sikh, a southeast Asian religion based on equality and unrelated to Islam.

But amid a new wave of anti-Islamic sentiment since the terror attacks in Paris and San Bernardino, Kaleka is vowing to take an entirely different approach.

"For us it does not matter who they're targeting," said Kaleka, a former Milwaukee police officer and teacher whose father was one of six people killed in 2012 when a white supremacist opened fire at a Sikh temple in Oak Creek, Wisconsin. "This time we cannot differentiate ourselves; when hate rhetoric is being spewed we cannot be on the sidelines."

Across the U.S., Sikhs and Muslims are banding together to defend their respective religions. Someone bent on harming Muslims wouldn't understand — or care — about the distinction between the two faiths, they say, and both also deserve to live in peace.

So they plan educational sessions and rallies. They successfully pushed the FBI to track hate crimes against Sikhs. They speak to lawmakers and support each other's legal action, including a lawsuit filed over a New York City police surveillance program targeting New Jersey Muslims.

"We are in this fight together," said Gurjot Kaur, a senior staff attorney at The Sikh Coalition, founded the night of Sept. 11.

Sikhism, a monotheistic faith, was founded more than 500 years ago in Southeast Asia and has roughly 27 million followers worldwide, most of them in India.

There are more than 500,000 Sikhs in the U.S. Male followers often cover their heads with turbans — which are considered sacred — and refrain from shaving their beards.

Reports of bullying, harassment and vandalism against Sikhs have risen in recent weeks.

Last week, a Sikh temple in Orange County, California, was vandalized, as was a truck in the parking lot by someone who misspelled the word "Islam" and made an obscene reference to ISIS.

A Sikh woman said she recently was forced to show her breast pump before taking her seat on an airplane in Minneapolis because another passenger thought she might be a terrorist. Schoolchildren say they've been bullied.

For most Sikhs, much of the backlash has been frequent stares or comments and occasional online insults.

Former NCAA basketball player Darsh Singh said he has heard insults throughout his life, including recently when someone recently yelled "Osama!" at him as he was crossing a street in Phoenix.

Then last week, a photo making the rounds on Facebook showed the former Trinity University basketball player — the first turbaned Sikh to play in the NCAA — with the caption: "Nobody wants to guard Muhammad, he's too explosive." A friend came to his defense with a lengthy post — saying, "do the world a favor and educate yourself" — which got tens of thousands of likes.

"A lot of people act out of fear or ignorance," said Singh. "I don't know who started it, but whoever they are, I forgive them."

Rajinder Singh Mago, community outreach director at the Sikh Religious Society of Chicago, said it's more difficult for Sikh schoolchildren who sometimes are bullied.

"Ninety-nine percent of Americans are good ... then that one person who just came out of a tavern after a few beers, you don't know what he's thinking at that point," Mago said.

Madihha Ahussain, a staff attorney at the national group Muslim Advocates, said people who are misinformed about both religions not only are "blaming entire faith communities, now they're blaming multiple groups for the acts of a couple individuals."

As a result, some Sikhs have encountered violence.

A Chicago-area teenager was charged with a hate crime after a September road rage incident in which he called 53-year-old Sikh taxi driver Inderjit Mukker "Bin Laden" and repeatedly hit him in the face, breaking his cheekbone.

In 2013, a Green Bay, Wisconsin, man was charged with a hate crime for allegedly setting fire to a convenience store owned by a Sikh-American.

That was less than a year after white supremacist Wade Michael Page killed six people and wounded four others at the Oak Creek temple. Kaleka said his father, Satwant Singh Kaleka, was the last person killed inside the temple, after Page broke into an office where the elder Kaleka was calling 911.

Kaleka said the Muslim community reached out to Sikhs in the aftermath, and members of both faiths — along with Christians, Jews and others — are continuing to work together to combat inflammatory rhetoric. Last weekend, he spoke at a Muslim women's coalition.

"I think this is just another test and, unfortunately, I think as bad as the comments are from some politicians, it does surface some underlying issues we haven't addressed," in this country, he said.