The U.S. Army's top officer spoke in his strongest terms yet about the harmful effects of automatic budget cuts on the military.

In comments that seemed directed more at lawmakers than soldiers, Army Chief of Staff Gen. Raymond Odierno said the service faces significant long-term challenges because of across-the-board spending reductions known as sequestration.

"Frankly, as I stand here, military risk is accumulating exponentially," he said during a speech on Tuesday at an annual conference in Washington, D.C., organized by the Association of the United States Army.

"We are reducing the size of our ground forces, we are not fully resourcing required readiness, and we are slashing our modernization and procurement programs," Odierno told a crowd of mostly military members and defense industry officials. "In my opinion, this is a time we should be increasing those investments. We should be reinvesting in order to rebuild and sustain a force capable of conducting the full range of operations."

Defense reductions will account for about half of the $1.2 trillion in decade-long spending cuts mandated by the 2011 Budget Control Act. While Congress agreed to undo some of those reductions in fiscal 2014 and 2015, the cuts are set to return in full in fiscal 2016.

After growing in size to 570,000 soldiers in 2008 at the height of the war in Iraq, the Army has about 510,000 soldiers today, according to Pentagon figures, and is on pace to shrink to 490,000 soldiers in fiscal 2015. It's bracing for even further contraction driven by sequestration and an end to the U.S.-led wars in Iraq and Afghanistan, where some 9,800 American troops will be serving by year's end.

The service's end strength is slated to decrease to 440,000-450,000 soldiers by 2017. If automatic budget cuts remain in effect, the number may fall to as low as 420,000 soldiers -- tens of thousands less than what Odierno has said is needed to adequately respond to conflicts around the world.

The general's comments echoed those he previously made about the rising national-security threats posed by Islamic militants, the Russian military and other groups. On Tuesday, he was even more direct about the harmful effects of shrinking the ground force, as well as the flawed assessments that went into those plans.

"As we continue to lose end-strength, our flexibility deteriorates, as does our ability to react to strategic surprise," Odierno said. "We are witnessing firsthand mistaken assumptions about the number, duration, location and size of future force conflicts and the need to conduct post-stability operations. These miscalculations translate directly into increased military risk."

Militants affiliated with the Islamic State in Iraq and Syria, known as ISIS or simply the Islamic State, an al-Qaida-inspired terrorist group that has overtaken swaths of Iraq and Syria, have in recent days overtaken a key military base in Anbar Province and advanced to several miles of Baghdad's airport.

At a separate panel discussion Tuesday morning, Army Materiel Command Commander Gen. Dennis Via said the funding uncertainty is exacerbated by such unforeseen contingencies. "The places we are today," he said, "we couldn't have predicted six months ago."

--Associate Editor Bryant Jordan contributed to this report.

-- Brendan McGarry can be reached at brendan.mcgarry@monster.com