"We've got to get the job done there," he said of Afghanistan. "And that requires us to have enough troops so that we're not just air-raiding villages and killing civilians, which is causing enormous problems there."
The comment drew a rebuke Tuesday from the campaign of Republican presidential candidate Mitt Romney.
"That is a very troubling remark on so many levels," said Romney spokesman Kevin Madden. "Most importantly, it's emblematic of Senator Obama's lack of experience for the job of commander-in-chief. But it's also an entirely inaccurate condemnation of the efforts of the men and women of the United States military who are serving in Iraq and Afghanistan."
A spokesman for Obama, who will speak at the Veterans of Foreign Wars convention in Missouri next week, did not immediately respond to Madden's criticism.
The flap comes three weeks after Obama promised that if elected president, he would meet without pre-conditions with the leaders of Iran, Syria, Venezuela, Cuba and North Korea. That pledge was called "irresponsible and frankly naive" by rival Democratic presidential candidate Hillary Rodham Clinton.
Eight days later, eager to rebut Clinton's charge, Obama said that as president, he might send U.S. troops into Pakistan to fight terrorists not targeted by Pakistani President Pervez Musharraf.
Critics called this overly hawkish, prompting Obama to modulate again the next day by ruling out the use of nuclear weapons to fight terrorism in Afghanistan and Pakistan.
"I think it would be a profound mistake for us to use nuclear weapons in any circumstance," he told the AP before pausing.
"Involving civilians," he added. "Let me scratch that. There's been no discussion of nuclear weapons. That's not on the table."
The gaffe was criticized by Clinton, who said: "I don't believe that any president should make any blanket statements with respect to the use or non-use of nuclear weapons."
Clinton has been criticized for a statement about Iran last year in which she said "I would certainly take nuclear weapons off the table."
On Tuesday, Clinton's campaign declined to comment on Obama's remark about U.S. troops in Afghanistan.
Officials Criticize Presidential Hopeful For 'Irresponsible' Comments on Military StrikesISLAMABAD, Pakistan, Aug. 3, 2007
Pakistani protesters burn a U.S. flag to condemn U.S. presidential hopeful Barack Obama's remarks, Friday, Aug. 3, 2007, in Karachi, Pakistan. Pakistan criticized Obama for saying that, if elected, he might order unilateral military strikes inside this Islamic nation to root out terrorists. (AP Photo/Shakil Adil)
Pakistan Fires Back At Obama
ISLAMABAD, Pakistan, Aug. 3, 2007
(AP) Pakistan criticized U.S. presidential candidate Barack Obama on Friday for saying that, if elected, he might order unilateral military strikes against terrorists hiding in this Islamic country.
Top Pakistan officials said Obama's comment was irresponsible and likely made for political gain in the race for the Democratic nomination.
"It's a very irresponsible statement, that's all I can say," Pakistan's Foreign Minister Khusheed Kasuri told AP Television News. "As the election campaign in America is heating up we would not like American candidates to fight their elections and contest elections at our expense."
Also Friday, a senior Pakistani official condemned another presidential hopeful, Colorado Republican Tom Tancredo, for saying the best way he could think of to deter a nuclear terrorist attack on the U.S. would be to threaten to retaliate by bombing the holiest Islamic sites of Mecca and Medina.
Obama said in a speech Wednesday that as president he would order military action against terrorists in Pakistan's tribal region bordering Afghanistan if intelligence warranted it. The comment provoked anger in Pakistan, a key ally of the United States in its war on terror.
Many analysts believe that top Taliban and al Qaeda leaders, including Osama bin Laden, are hiding in the region after escaping the U.S.-led invasion of Afghanistan in 2001.
President Gen. Pervez Musharraf has come under growing pressure from Washington to do more to tackle the alleged al Qaeda havens in Pakistan. The Bush administration has not ruled out military strikes, but still stresses the importance of cooperating with Pakistan.
"There are terrorists holed up in those mountains who murdered 3,000 Americans. They are plotting to strike again," Obama said. "If we have actionable intelligence about high-value terrorist targets and President Musharraf will not act, we will."
The Associated Press of Pakistan reported Friday that Musharraf was asked at a dinner at Prime Minister Shaukat Aziz's house on Thursday about the potential of U.S. military operations in Pakistan. Musharraf told guests that Pakistan was "fully capable" of tackling terrorists in the country and did not need foreign assistance.
Deputy Information Minister Tariq Azim said no foreign forces would be allowed to enter Pakistan, and called Obama irresponsible.
"I think those who make such statements are not aware of our contribution" in the fight on terrorism, he said.
Pakistan used to be a main backer of the Taliban, but it threw its support behind Washington following the Sept. 11, 2001 attacks.
Since then, Pakistan has deployed about 90,000 troops in its tribal regions, mostly in lawless North and South Waziristan, and has lost hundreds of troops in fighting with militants there.
But a controversial strategy to make peace with militants and use tribesmen to police Waziristan has fueled U.S. fears that al Qaeda has been given space to regroup.
In Pakistan's national assembly on Friday, Minister for Parliamentary Affairs Sher Afgan said he would bring on a debate next week on recent criticism of Pakistan from several quarters in the U.S., including Tancredo's remarks.
It was a matter of "grave concern that U.S. presidential candidates are using unethical and immoral tactics against Islam and Pakistan to win their election," Afghan said.
Tancredo told about 30 people at a town hall meeting in Osceola, Iowa, on Tuesday that he believes that a nuclear terrorist attack on the U.S. could be imminent and that the U.S. needs to hurry up and think of a way to stop it.
"If it is up to me, we are going to explain that an attack on this homeland of that nature would be followed by an attack on the holy sites in Mecca and Medina. Because that's the only thing I can think of that might deter somebody from doing what they otherwise might do," he said.