Officials from the White House's Office of Management and Budget said that the military spending figure was not fixed and could be altered if more money was required.
With $50bn already authorised, the new request would take the total of supplemental military spending to $120bn for 2006.
In a separate move, the administration will ask for a 5 per cent increase in the Pentagon's budget. This budget request includes more than $80bn to be spent on weapons systems and means the annual total budget request for the Pentagon will be $439.3bn.
The Pentagon plans to increase special operations forces by 15 per cent, including the establishment for the first time of a Marine Corps commando unit.
And there will be a one-third increase in troops assigned to psychological warfare units.
Joel Kaplan, the office's deputy director, said the bulk of the $70bn in military spending would be spent on operations, including pay and benefits for National Guardsmen, fuel and spare parts.
But he added that a large proportion of the request was required to overhaul or replace equipment that was worn out. Some of the funds will go towards new equipment and technology that can protect US troops against roadside bombs.
Bryan Whitman, a Pentagon spokesman, said that the request reflected the President's desire to "commit the resources that are necessary to fight and win the war on terrorism".
Mr Whitman said the extra $70bn is on top of $320bn spent since 2001 to fund military operations in Iraq and Afghanistan. He said the cost of US military operations - not including the purchase of new equipment - was running at $4.5bn a month in Iraq and $800m in Afghanistan.
Some campaigners condemned the vast amount being spent on the military and said the money would be better used to improve social programmes at home.
Kathy Kelly, a veteran peace campaigner with Voices in the Wilderness, said: "[Though] spending our wealth and productivity on military matters never appears to be questioned at an ethical level, I think politicians from all sides could question it from a practical level."
She added: "We have 45 million people without health insurance, infrastructure is crumbling, mass transit is an illusory goal."
The additional spending to help those affected by Hurricane Katrina, which caused flooding that devastated New Orleans and large parts of the Gulf Coast in August last year, will bring the total spent by the government on such relief to $100bn.
The money was welcomed by local politicians. But some voiced concern that the money - directed towards the much-criticised Federal Emergency Management Agency (Fema) - would not be spent in the correct way.
Senator Mary Landrieu, a Louisiana Democrat, said: "We certainly welcome additional federal assistance. But I am highly concerned that the administration's proposal, which lacks details, will put more money into dysfunctional federal bureaucracies like Fema and won't adequately address urgent needs such as housing, levees and flood protection."