President Barack Obama's defense budget invests heavily in medical care and morale-boosting programs for US soldiers and their families amid the mounting strain of more than eight years of war.

The 2011 budget unveiled on Monday and a Pentagon strategy review put a spotlight on the emotional and financial burden placed on the all-volunteer force since the attacks of September 11, 2001.

The budget calls for 30.9 billion dollars for medical care, including 669 million to treat traumatic brain injury and psychological problems as well as 250 million for research into mental health and suicide prevention measures.

Military leaders have called traumatic brain injuries and post-traumatic stress disorder the "signature wounds" of the wars in Iraq and Afghanistan, and have struggled to contain a steady rise in suicides.

The budget promises quality care for the more than 36,000 soldiers wounded in Iraq and Afghanistan, including funds for "wounded warrior transition units" that try to help service members recover from their injuries.

The Pentagon's long-term strategic outlook, due to be rolled out on Monday, also highlights the stress produced by repeated deployments and the need to assist military families as well as replace worn out equipment.

Previous strategy reports have tended to focus on weapons and global trends, but the administration's Quadrennial Defense Review (QDR) also underscores the importance of caring for the morale and health of soldiers and their families.

"In order to succeed in today's wars and prepare for the future, the Department of Defense must ensure the long-term viability of the all-volunteer force, its most precious military resource," according to a draft of the review.

The cost of maintaining the volunteer force, which has expanded under the demands of the Iraq and Afghan conflicts, is steadily rising, with large sums spent on salaries, bonuses and medical care.

Military health care costs have mushroomed over the past decade, reflecting a spike in the country at large, and some defense analysts say the personnel costs could put a squeeze on spending for hi-tech weapons.

Medical costs account for about six percent of the Pentagon's current budget and are forecast to exceed 10 percent in 2015, the draft QDR said.

First Lady Michelle Obama has made a point of raising awareness about the plight of military families and last week -- before the budget was released -- touted more federal funds for child care, housing and education for spouses.

The budget calls for more than eight billion dollars to support military families, a three percent increase over the last defense budget, including money for affordable child care, counseling services and help with tuition costs for spouses, the White House said.

"These are all major investments," Michelle Obama told an audience of military spouses last week.

"They are the result of military families speaking up and being heard. And they are part of a larger ongoing commitment to care for our troops and their families even after the fighting ends."

The wars in Iraq and Afghanistan have already cost one trillion dollars since 2001, and the new budget calls for roughly 159 billion dollars to cover the costs of the US missions there -- including about 11.6 billion to expand the Afghan security forces.

The US president also has asked for an extra 33 billion dollars for the current fiscal year to cover the cost of a surge of 30,000 troops into Afghanistan.