Army soldiers mourn the loss of one of their own, an unfortunate reality of military service. AP

Since 2009, $287 million has been spent on programs aimed at improving morale within the US military, which has shouldered two major overseas combat deployments over the past decade.

But these efforts may have been largely fruitless, as 52% of soldiers across all branches remain "pessimistic about their future in the military," according to an April USA Today report.

For decades, analysts have consistently reported on supposedly declining US military morale, even before the wars in Iraq and Afghanistan.

A Brookings Institution report notes: "Observers regularly fretted over low morale during the defense drawdown of the 1990s, during the start of the Iraq War, during the Iraq Surge, during the Afghanistan Surge; and at practically all the points in between ... After each report of troop morale hitting 'rock bottom,' troop morale seems to slip lower yet and, still, the military soldiers on."

In the past, flagging morale may have been attributable to factors like repeated Iraq or Afghanistan deployments.

But a 2014 Military Times study suggests a financial cause for flagging morale: "In 2009, 87 percent of active-duty troops who participated in Military Times' survey rated their pay and allowances 'good' or 'excellent,'" the newspaper reported. "This year, the figure was just 44 percent."

The US government increased military pay just 1 percent in 2014, the smallest hike in 41 years and down from a 3.9 percent raise in 2009 and a 6.9 percent jump in 2002, according to the Military Times.

Soldiers from the 454th Engineer Company Route Clearance go on a patrol in Sayghani, Parwan province, Afghanistan, Sept. 27, 2014. The reason for the patrol was to gather intel on the indirect fire attacks happening at Bagram Air Field. Staff Sgt. Daniel Luksan/US Army

Few of the soldiers polled believed their situation would improve: 70 percent of those Military Times surveyed said that they expected quality of life under military employment to decrease further in the future.

Pay and benefits aren't the only cause of pessimism in the ranks. Some in the military worry that the the armed forces aren't being adequately led into the future, and declining morale could signal a general lack of confidence in the military's leadership.

MSNBC reports that in 2011 "only 26 percent of Army leaders who participated agreed with the statement that the Army 'is headed in the right direction to prepare for the challenges of the next 10 years.'"

According to the Military Times, only 27 percent of soldiers thought that leadership had their best interests at heart.

Despite years of sustained effort to withdraw troops, a US presence is still needed in Iraq. Mike Lavigne/US Army

President Obama is unpopular with the armed forces as well, though some of his administration's policies have gained support over the years.

A separate Military Times poll found Obama's popularity at a dismal 15 percent among soldiers in 2014. Morale is bound to decline if soldiers don't believe in their commander-in-chief.

But there's also information in the poll suggesting that that low number actually underestimates the president's approval among military personnel: in the last 5 years, approval for some of Obama's military policies, like ending Don't Ask Don't Tell and opening combat units to women, have gained support, seeing a 30 percent rise in popularity.

There's another possible reason for drooping morale, especially among soldiers who fought in either Iraq or Afghanistan: It may be hard for some military personnel to see their work as effectual while ISIS becomes a deadly and rising force throughout the Middle East.

Much of the territory that US troops fought and died to establish a democracy in now is in the hands of ISIS. The Institute for the Study of War

Whether it's because of stagnant pay, stale leadership, Obama's supposed unpopularity, or the state of global geopolitics, the US military may have a very challenging problem on its hands.