Budget cuts are hampering the American military’s ability to defend the nation’s interests and its leaders must decide if the United States will continue to exercise global leadership, defense experts said Tuesday.

Some observers have pointed to recent congressional opposition to military strikes in war-torn Syria as evidence of broader shift by lawmakers, backed by a war-weary public, away from U.S. intervention in overseas conflicts.

Republicans, traditionally more hawkish on defense issues, have also sought to preserve what they have called "historic cuts" to the military in the 2011 Budget Control Act. That act eventually resulted in sequestration, which removes nearly $1 trillion from the defense budget in the next decade.

Eric Edelman, former U.S. ambassador and under secretary of defense for policy, said recent actions by lawmakers from both parties might signal a divergence from long-standing U.S. foreign policy goals of defending the homeland, maintaining freedom on the seas and a balance of power in regions like the Asia-Pacific, and assisting with international humanitarian needs.

"Those are still things the United States needs to be able to do," he said at a forum hosted by the Foreign Policy Initiative. "It’s something we have done for the last 60 years. We have provided for the public good."

Edelman noted that the U.S. was "able to generate considerable savings" after previous military drawdowns following World War II and the Korean and Cold Wars.

However, he said the current situation is different because force levels have not increased significantly in recent years while personnel costs have skyrocketed.

"We have to get at the embedded costs," he said. "It’s really a microcosm of the entitlement problems we face as a nation inside the defense budget."

According to a recent report by the Bipartisan Policy Center (BPPC), personnel, health care, and other defense-wide costs will consume virtually 100 percent of the Pentagon’s budget by 2021, leaving almost no funds for force additions, troop training, or equipment upgrades.

Sequestration also largely spares spending on major entitlement programs like Social Security, Medicare, and Medicaid, which will absorb 60 percent of the overall U.S. budget by 2022, according to the BPPC report. Discretionary defense spending will account for just 13 percent by comparison.

Budget realities will require some tough choices by the armed services, said retired Gen. John Allen, former commander of U.S. forces in Afghanistan.

"The services will have to make a choice among readiness, modernization, and size that can permit a force at the end of 13 years of conflict to reinforce the core competencies that we need," he said.

The juggling act has already begun to affect the Obama administration’s planned "pivot" toward the Asia-Pacific region, said Rep. Randy Forbes (R., Va.), chairman of the House Armed Services Subcommittee on Seapower and Projection Forces.

That strategy calls for shifting 60 percent of U.S. naval assets to the region by 2020 to promote trade and show support for treaty allies currently engaged in territorial disputes with China in the South and East China Seas.

"When I hear anyone talk about the Asia-Pacific ‘pivot’ or ‘rebalance,’ the first thing that I see that’s missing is the capabilities," Forbes said. "If you look, we really have a huge disconnect between the topic itself and actual capabilities that are put there to try to implement that policy, whatever it might ultimately be."

Crises in nations like Syria also continue to divert U.S. attention from the region, experts at the forum said.

Rep. Mike Rogers (R., Mich.), chairman of the House Permanent Select Committee on Intelligence, described the Syrian conflict as "a classic case of why we need to reengage in the world."

Although President Barack Obama urged Syrian President Bashar al-Assad to "step aside" in 2011, officials were reluctant to aid opposition rebel groups with covert training and arms shipments, Rogers said.

Thousands of Sunni Muslim jihadists have streamed into Syria to oppose Assad, a member of the Alawite sect of Shiite Islam. Iran has in turn bolstered the Assad regime through its proxies, the Lebanese terrorist group Hezbollah and Shiite militias from Iraq.

Rogers said there are security interests at stake for the West: Many of the jihadists are foreign fighters that could eventually return home to the U.S., Europe, and elsewhere "combat trained and combat hardened," he said.

"We said after 9/11: no more safe havens, we are never going to allow it," he said. "What we have happening in Syria today is the development of maybe the largest safe haven, without our ability to conduct operations, that we have ever seen. That should concern all of us."

Rogers has proposed arming and training more moderate elements of the Syrian opposition.

He also expressed little hope that peace talks scheduled for next month, which have been continually postponed since May, would convince Assad to step down as he consolidates gains on the battlefield.

The U.S. faces another test of its willingness for continued global engagement in Afghanistan.

Officials have reached a tentative agreement with Afghan President Hamid Karzai to retain a small advisory force in the country after the withdrawal of combat troops at the end of 2014, pending approval from an assembly of tribal elders or Loya Jirga and the Afghan parliament.

The U.S. was unable to reach a similar type of agreement in Iraq in 2011. There has since been a resurgence of al Qaeda in Iraq, experts say, resulting in thousands of deaths in recent months.

"You have now an al Qaeda in Iraq franchise that is back to the level of car bombing that it was conducting at the height of the surge in 2007 before the violence came down," said Frederick Kagan, director of the American Enterprise Institute’s Critical Threats Project. "That has all happened since American forces withdrew."

Kagan noted that al Qaeda has expanded its operations and affiliates since before 9/11, another reason for the U.S. to remain engaged after the close of the Iraq and Afghanistan wars, he said.

"The tide of war is not receding," he said. "The tide of American desire to be involved in war is receding.

"We may be tired of war, but war is not tired of us."