WASHINGTON — The Department of Defense will be extending certain benefits to same-sex couples in the military, a move announced Monday in a memorandum by Secretary Leon Panetta — a final punctuation mark to the outgoing defense secretary's tenure at the Pentagon.

"Our work must now expand to changing our policies and practices to ensure fairness and equal treatment and to taking care of all of our service members and their families, to the extent allowable by law," Panetta wrote of the post-"don't ask, don't tell" military in the memo.

The Defense of Marriage Act prohibits the federal government recognizing same-sex couples' marriages limits those benefits, but both the Pentagon and advocacy groups had identified several benefits that could be extended, from joint duty assignments for couples in which both partners are in the military to allowing servicemembers' same-sex domestic partner to have a military identification card.

Although several such benefits were extended — from those two areas to benefits involving commissary privileges and family programs — neither on-base housing nor burial benefits were granted by today's memo. Secretary Panetta said their issuance involved "complex legal and policy challenges" and would continue to be reviewed.

An implementation plan for the new benefits will be issued in the next 60 days, with the expansion of the benefits, per Panetta's memo, to take effect sometime between August 31 and October 1.

President Obama, who has received some pressure on the issue, "welcomes the announcement by the Secretary of Defense that the Department will extend certain benefits to the same-sex partners and families of service members based on its thorough and deliberate review of this issue," White House spokesman Shin Inouye told BuzzFeed. "This step will strengthen our military and help ensure that all our troops and their families are treated with fairness and equality."

Sen. John McCain, who had opposed the repeal of the military's ban on out gay service but had not continued his opposition since the change was implemented, reacted without fanfare or opposition to the benefits announcement Monday afternoon, saying only, "I respect their decision."

Activists likewise hailed the decision. "Today, the Pentagon took a historic step forward toward righting the wrong of inequality in our armed forces, but there is still more work to be done," Human Rights Campaign President Chad Griffin told BuzzFeed. "Gay and lesbian service members and their families make sacrifices every day, and this country owes them every measure of support we can provide. Since the repeal of 'Don't Ask, Don't Tell,' the Obama administration has shown true leadership on this issue."

The issue of same-sex partner benefits has been one of three main issues pushed by advocacy groups like OutServe-SLDN since the end of "Don't Ask, Don't Tell" in September 2011. The benefits issue, along with an explicit nondiscrimination policy and an end to the ban on out transgender service, were not addressed in the legislation passed by Congress and signed into law by President Obama in December 2010. Asked whether there was any plan to expand the nondiscrimination policy to include sexual orientation, a senior Defense Department official briefing the media Monday on background said there was no such plan.

Of today's action, OutServe-SLDN executive director Allyson Robinson said, "Secretary Panetta's decision today answers the call President Obama issued in his inaugural address to complete our nation's journey toward equality, acknowledging the equal service and equal sacrifice of our gay and lesbian service members and their families. We thank him for getting us a few steps closer to full equality — steps that will substantively improve the quality of life of gay and lesbian military families."

In recent months, a situation in which the same-sex wife of an Army officer was not allowed to join a spouses' group that met at the Fort Bragg installation highlighted the ongoing issues with the military's treatment of gay, lesbian, and bisexual servicemembers.

In addition to the benefits extended today, the advocacy group OutServe-SLDN has an ongoing lawsuit against the Pentagon and Department of Veterans Affairs challenging DOMA to the extent it limits military and veterans' spousal benefits. Although the Obama administration has not been defending that lawsuit, the House Republican leadership has taken up the defense of DOMA in the case as it has in other challenges to the 1996 law.

As recently as Friday night, the government response to inquiries over the past year had been that "the Department of Defense is conducting a deliberative and comprehensive review of the availability of benefits, when legally permissible, to same-sex domestic partners of service members."

While the Pentagon's decision was historic, activists weren't wasting any time calling for further action.

"Even today, the discriminatory Defense of Marriage Act makes inequality for gay and lesbian military families a legal requirement. It's time to right this wrong. When the Supreme Court considers the constitutionality of DOMA in the coming weeks … [it] should reflect on the sacrifice made by Americans like Staff Sergeant Tracy Johnson, whose wife was killed in action late last year, or the family of Chief Warrant Officer Charlie Morgan, who succumbed to cancer earlier this week," Griffin said.

The ongoing Supreme Court challenge to the definition of "marriage" and "spouse" in DOMA also means that the groundwork that is the basis for the limits to this expansion could change by June, when the final Supreme Court decisions of the term are generally issued.

To that end, Panetta wrote in Monday's memo, "In the event that the Defense of Marriage Act is no longer applicable to the Department of Defense, it will be the policy of the Department to construe the words 'spouse' and 'marriage' without regard to sexual orientation, and married couples, irrespective of sexual orientation, and their dependents, will be granted full military benefits." The memo notes that, should that happen, the Pentagon will reassess whether to continue to allow "unmarried same-sex domestic partnerships" being the basis for eligibility of the benefits extended Monday.