The collapse of Iraq's armed forces in the face of a lightning advance by Islamic militants has left some Lowcountry veterans of the Iraq war, incuding the Army general who helped pave the way for the U.S. invasion in 2003, frustrated, saddened and disappointed.

"I'm very sad about what could have been and what appears is now happening," retired Lt. Gen. Colby Broadwater, who commanded operations in northern Iraq and Turkey in early 2003, said Friday. "We lost the better part of 4,000 soldiers in that operation. The Iraqis lost a lot of people. We have put untold billions of dollars into assisting and stabilizing that nation, which is a very difficult thing, to build a nation, and now it appears it's all falling apart."

Broadwater, now president of the American College of the Building Arts in Charleston, worked closely with American and Iraqi leaders, including current Iraqi Prime Minister Nouri al-Maliki, to organize Iraq's new government after the overthrow of Saddam Hussein's regime.

"We caused a change, we set up the government, and in my opinion, we left that government ill-prepared to handle the huge challenges that they faced," he said.

Broadwater said he believes it may be too early too tell whether the situation is a lost cause, but that further U.S. intervention would be difficult.

"The last time, it took months of planning. The situation is totally different," he said. "You would have to figure out what U.S. policy is and then develop a strategy to implement that policy. There may not be enough time to do that."

In a televised address Friday, President Barack Obama ruled out sending U.S. troops back to Iraq, but said all other options are being considered to blunt the advance of the Islamic State of Iraq and Syria, which had taken several northern cities and was threatening Baghdad.

Other veterans who fought in Iraq said they weren't surprised at how quickly the militants have gained the upper hand.

"I find it laughable that this administration, this government, was caught off-guard by what's happening there now," said retired Master Sgt. Denny Sherrod, a Pendleton and Folly Beach resident. "And then they stand around and wring their hands and say, 'We're going to do this, we're going to do that.' We're not going to do anything."

Sherrod, who served in Vietnam and retired from the Army Reserve after serving in operations Desert Shield and Desert Storm, said he thinks the attacks will lead to a "steadily expanding, multination civil war.

"When your biggest source of support withdraws, it leaves a vacuum, and the vacuum that's left behind drags all these bad guys in," he said at American Legion Post 147 on James Island. "This administration has steadily given away whatever leverage they had in the region. Every good deed that this nation was involved in has been thrown away, and a lot of American lives with them."

This week's stunning advance left many U.S. veterans around the nation reflecting - with bitterness, frustration and sadness - on the sacrifices of a war that lasted for more than eight years and killed nearly 4,500 Americans and tens of thousands of Iraqis.

"In many ways it just feels like a waste - a waste of many lives, a waste of many years," said retired Army Col. Barry Johnson from his home in Potlatch, Idaho.

On the broad stage of Middle East affairs, the unraveling highlights the resilience of extremists and the risks of weakened central authority. But it's in the small settings across America - the American Legion on James Island, VFW posts, rehabilitation clinics, kitchen tables - where a different type of reckoning is taking place. Soldiers and commanders who served in Iraq struggle to make sense of the unfolding chaos.

Martin Schaefer, an Army reservist who did two tours in Iraq, groped for the right word to define his emotions near his home in Darien, Ill. Not mad or upset, he said.

"Sad," he decided. "Sad to see that the work that had been accomplished by the U.S. and Iraqi forces is being undone by an insurgency."

The Associated Press contributed to this report.