WASHINGTON (CNN) -- President Bush on Monday said there would be no quick U.S. exit from Iraq despite his concerns over talk of civil war in the country and the effect the war is having in American society.
"If we ever give up the desire to help people who want to live in a free society, we will have lost our soul as a nation," Bush said.
"Sometimes I'm frustrated, rarely surprised," Bush said of events in Iraq. "Sometimes I'm happy."
"A war is not a time of joy," he said. "These are not joyous times. These are challenging times and they're difficult times. And they're straining the psyche of our country. I understand that."
But defeat is unacceptable, he said.
"Chaos in Iraq would be unsettling in the region," he said. "Leaving before the job is done would be a disaster."
"I hear a lot of talk about civil war. I'm concerned about that, of course," Bush said, citing Iraq as part of what he called "a global war on terror."
"A failed Iraq in the heart of the Middle East will provide safe haven for terrorists and extremists. It will embolden those who are trying to thwart the ambitions of reformers.
"In this case, it would give the terrorists and extremists an additional tool besides safe haven, and that is revenues from oil sales."
Bush: Hezbollah must not re-arm
Bush also called Monday for an effective international force in Lebanon to ensure Hezbollah doesn't re-arm and "wreak havoc in the region."
"The need is urgent," Bush said.
"The international community must now designate the leadership of this new international force and give it robust rules of engagement and deploy it as soon as possible to secure the peace," said Bush, speaking at the beginning of a Washington news conference Monday morning.
"Our nation is wasting no time in helping the people of Lebanon," Bush said, detailing U.S. efforts to get humanitarian aid, including food and energy, into Lebanon.
Bush also announced aid for rebuilding homes and schools in Lebanon, and he announced aid to help Israeli civilians recover from Hezbollah rocket strikes.
U.N. Envoy Terje Roed-Larsen said Sunday that Lebanon faces opportunity and danger as it tries to recover from 34 days of fighting between Hezbollah guerrillas and Israeli troops.
About 3,000 Lebanese troops and a handful of international troops -- the first in a force of 15,000 -- have moved into southern Lebanon to ensure Hezbollah does not launch rockets into Israel.
Italy has volunteered to send 3,000 troops for the U.N. force, but other European nations have not offered significant commitment, including France, which is adding just 200 troops to the 200 it has now in Lebanon.
"We're at the tilting edge still, and this can easily start sliding again and lead us quickly into the abyss of violence and bloodshed. This is why diplomacy is so important," Roe-Larsen said.
Bush cited Iranian support for Hezbollah, which the U.S. considers a terrorist organization, as one example of why Iran cannot be permitted to have nuclear weapons capability.
'Iran is obviously part of the problem'
"Iran is obviously part of the problem," Bush said. "They sponsor Hezbollah. They encourage a radical brand of Islam. Imagine how difficult this issue would be if Iran had a nuclear weapon.
"So therefore it's up to the international community including the United States to work in concert for effective diplomacy. And that begins at the United Nations Security Council," Bush said.
The Bush administration reiterated Monday that Iran must adhere to a August 31 deadlines to halt uranium enrichment.
"Iran faces a clear choice," a White House statement released earlier Monday. "Iran has until August 31 to respond to the Security Council's mandate to suspend all enrichment related and reprocessing activities.
"We have made clear that if Iran fails to comply with the Security Council's mandate, we will move quickly at the United Nations to impose sanctions."
Earlier Monday, Iranian state television reported that the country's supreme leader, Ayatollah Ali Khamenei, said Tehran will continue to pursue nuclear technology and not give in to "arrogant powers and the U.S." (Full story)
Khamenei's declaration came on the eve of Iran's self-imposed August 22 deadline to respond to a Western incentives package for it to roll back its nuclear program.
Monday's news conference was Bush's first in Washington since June, but he also had a news conference in Chicago July 7.
Meanwhile, new poll numbers Monday give Bush a bit of a boost.
Forty-two percent of respondents in the Opinion Research Corporation poll released Monday approve of the way Bush is doing his job, up from 40 percent in an early August poll but still within the poll's 3 percent margin of error.