Secretary of State Hillary Clinton unveiled the deal, which is subject to Congressional approval.
But the Obama administration will make clear it expects Islamabad to do more in the fight against Islamic militants.
The US has given Pakistan more than $1bn of military aid a year since 2005; last fiscal year, it gave nearly $2bn.
US officials said Pakistan needed further, specific assistance for the fight against militants and needed to know it could rely on the US in the long term.
So unlike previous military aid approved on a yearly basis, this is a five-year package.
The aid will pay for equipment needed in counter-insurgency and counter-terror operations, among other things.
'Reducing threats to US'
Vali Nasr, a senior adviser on Pakistan and Afghanistan at the state department, told the BBC that the battle against Pakistani militants had expanded over the last year, but the summer's monsoon floods had undone a lot of the Pakistani army's efforts.
"We believe that we have made a great deal of progress and we believe that that progress has reduced the threat to our homeland, while not eliminating it," Richard Holbrooke, the US special representative on Afghanistan and Pakistan, said this week.
But officials in Washington have also been frustrated at the limits of Pakistan's desire and ability to help.
A White House report sent to Congress earlier this month lamented the Pakistani army's inability to hold territory it had seized from insurgents, a failure that means gains are likely to be short-lived.
"The Pakistan military continued to avoid military engagements that would put it in direct conflict with Afghan Taliban or al-Qaeda's forces in North Waziristan," the report said, referring to the region in north-western Pakistan seen as a Taliban and al-Qaeda haven.
"This is as much a political choice as it is a reflection of an under-resourced military prioritising its targets."
The report also said the civilian leadership did not have the trust of the people and faced "broad-based" challenges that had "the potential to impact the stability of the government".
Mr Nasr said the solution was not to withdraw US investment from Pakistan, but rather to help the Pakistani government and military strengthen the country's institutions.
The Pakistani government is in fact crucial to that strategy, and this can make Washington vulnerable.
A crisis in ties between the two countries last month has highlighted the fine line the Obama administration must walk as it cajoles and pressures its ally.
After at least two Pakistani troops were killed in a Nato cross-border attack in September, a furious Islamabad blocked the main transit route for military supplies to Afghanistan until it received a formal apology.
During the row, dozens of lorries laden with fuel and supplies were destroyed by militants in Pakistan while en route to the frontier.
The US-Pakistan strategic dialogue, which started last year, is designed to build trust and keep the conversation going between the two countries, not just about security, but about a wide range of issues from healthcare to education and water projects.
'Not enough sticks'
The five-year package announced on Friday is meant to complement a $7.5bn package of civilian aid over five years that was approved by the US in 2009.
It is all designed to reduce Islamic militants' allure and to win Pakistanis' hearts.
"We want to expand the security relationship that Pakistan and the US had in the past under the Bush period to be much broader," Mr Nasr said, "to involve things that also matter to Pakistanis and impacts their daily lives.
"A relationship means that we don't focus only on things that are important to us, but also things that are important to Pakistanis.
"Average Pakistanis have to see value in their engagement with the US before they subscribe to that relationship."
But some question the Obama administration's approach, saying there are too many carrots and not enough sticks, and not enough conditions attached to the carrots.
In a piece published in the New York Times this week, the former ambassador to Afghanistan, Zalmay Khalilzad, urged Washington to "offer Islamabad a stark choice between positive incentives and negative consequences".