Sikh Coalition, an advocacy group, plans to deliver a letter from the military leaders, including a retired three-star US Army general, to Defence Secretary Ash Carter saying Sikh Americans "should be given equal opportunity to serve."
"The US Department of Defence has taken important steps toward recognizing the importance of religious faith to the lives of our service members," said the letter as cited by the Wall Street Journal.
"Nevertheless, obstacles remain for patriotic Sikh Americans who wish to serve in our nation's military while maintaining their articles of faith."
They are asking that the military find a more reasonable way for Sikhs to serve without going through what they describe as a long, difficult process of getting an exemption allowing turbans and beards.
In some cases, a military service branch may require a Sikh to shave his beard and remove his turban while waiting for the exemption, the Journal noted.
In the 1980s, the military established regulations that require service members to adhere to uniformity rules about appearance, including hair and grooming standards that prohibit beards and headwear.
Since 2009, the military has allowed three Sikhs to serve in the US military wearing turbans
Among them Maj. Kamaljeet Singh Kalsi, 39, was awarded the Bronze Star for his work as the medical officer running the emergency room at Camp Dwyer in Helmand province, Afghanistan, in 2011.
Kalsi told the Journal his accommodation took 15,000 petitioners, 50 congressional signatures and a year and a half "just to get one guy in"-an onerous process that discourages many Sikh Americans.
Meanwhile, Joe Crowley, Vice Chair of the Democratic Caucus in the US House of Representatives, has welcomed the call by 27 retired US military leaders to allow Sikh Americans to serve in the military with their turban and beards.
"Sikh Americans love this country and want a fair chance to serve in our nation's military - we should embrace this wish, not place restrictions on it," he said.
"I will continue my efforts to end the presumptive ban on service by Sikh Americans so that those who want to serve, can serve," Crowley said. "It is time for our military to make inclusion of practicing Sikh Americans the rule, not the exception."
Last year, Crowley and Republican House member Rodney Frelinghuysen led over 100 Members of Congress in a bipartisan letter to the Department of Defence urging the US Armed Forces to update their appearance regulations to once again allow Sikh Americans to serve while abiding by their articles of faith, such as wearing a turban or beard.