President Bush called on the United Nations Wednesday to lift economic sanctions against Baghdad now that Saddam Hussein's regime has collapsed.

In a speech at Boeing Co. in St. Louis, Bush said the Iraqi people are reclaiming their own future.

"Thanks to the courage and might of our military, the American people are now secure," Bush said. "Thanks to the courage and might of our military, the Iraqi people are now free."

The United Nations has held sanctions over Iraq's head since its 1990 invasion of Kuwait. The measures were said to have greatly hurt the Iraqi people without doing much damage to the regime, despite the U.N. oil-for-food program that allowed Iraq to sell some oil in exchange for humanitarian aid for the people.

"The lives of the Iraqi people will be better than anything they have known for generations," Bush said.

Speaking to workers at the jet manufacturer, Bush promised to help rebuild Iraq, tighten the grip on terrorists around the world and put more Americans to work.

Earlier in the day, Bush signed into law an $80 billion wartime spending bill that was approved by Congress last week. The package gives him more money than he had asked for but adds more stringent controls on how he can spend it.

Bush also approved lowering the nation's threat level to yellow, which means "elevated," from the second highest threat of orange.

The threat level's reduction coincides with the capture of several terrorists, most notably Abu Abbas, who was taken in a raid in Baghdad on Monday night. Abbas is the mastermind of the Achille Lauro cruise ship hijacking in 1985 in which one American died.

Bush told any "terrorists and tyrants" who might be listening that the United States is on the offensive now against any person or group that poses a serious threat to its interests.

"On Sept. 11, 2001, America found we are not immune to the threats that gather for years across the oceans," he said. "America and its friends and its allies will act in our defense … we will protect our security and we will promote the peace in the world."

The president is using the success of the U.S.-led military campaign to send a warning to other nations that harbor terrorists or weapons of mass destruction that now that the United States has the precision-guided arms used so effectively in Iraq, they can no longer hide behind human shields and non-military sites.

The warning may have been heard by North Korea, which agreed to multilateral talks with China and the United States next week to address the secret and illegal nuclear weapons program that North Korea has maintained over the past decade. That is a switch from the pre-Iraq days when North Korea said it would deal only directly with the United States.

Bush administration officials consider the turnaround by North Korea an early dividend of the military success in Iraq. The president also wants Japan and South Korea to participate in the meeting. An official said including those two nations "will be essential to reach substantive results that we are seeking."

At the Boeing factory, which makes one of the fighter jets that flew missions during the Iraq conflict, Bush donned clear safety glasses and walked the factory floor where workers assemble the front half of the F/A-18 Super Hornet. The rear is made by Northrop Grumman.

Just deployed in July 2002, three squadrons of the jets are aboard the aircraft carriers USS Abraham Lincoln and USS Nimitz, Boeing spokeswoman Patricia Frost said.

Bush told the Boeing workers and military personnel at the site that they were vital to the war effort half a world away and hailed the technological advances that have produced a superior U.S. military force.

"Our work is not done, the difficulties have not passed but the regime of Saddam Hussein has passed into history," Bush said. "Each of you has had a part in preparing this nation for meeting the terrors of our time."

Though Bush signed the $80 billion war spending package, he was left with only limited control of the nearly $63 billion earmarked for the Pentagon. A House-Senate compromise slashed the money in his complete control to $15 billion. Lawmakers also voted to require Bush to let them know exactly how he will spend the money five days before he hands it out.

On Wednesday, the Pentagon announced that it has spent $20 billion so far on the war in Iraq, which started less than a month ago and is largely over. About $10 billion has been spent on operations, $4 billion on personnel movement, $3 billion on munitions and equipment and $2 billion for personnel support.

Under Secretary of Defense Dov Zakheim, speaking during the Pentagon briefing, estimated that it will cost more than $2 billion per month to maintain a military presence in Iraq.

The president did win from Congress the power to give the Pentagon and other agencies a role in spending some of nearly $2.5 billion for rebuilding Iraq and providing humanitarian aid there. Some lawmakers wanted the money to go to the State Department.

The spending bill also includes money to fight terrorism and bolster homeland security, and it provides about $3 billion for the struggling airline industry that, since the Sept. 11 terrorist attacks, just can't seem to catch a break.

The Boeing address was Bush's second address in two days to push his $726 billion economic package, which the president said would jumpstart the nation's economy.

He said the benefit of the package "starts with letting you keep more of your own money."

Most Democrats and even some moderate Republicans in Congress have questioned the wisdom of slashing taxes while deficits are rising and Iraq is being rebuilt.

Democrats have also criticized Bush for meeting with Boeing employees so soon after he opposed extending unemployment insurance for workers in the aviation industry.

The unemployment rate for that beleaguered industry is three times the national average. Boeing slashed 30,000 jobs by the end of 2002 and said it would eliminate another 5,000 positions, mostly in the commercial airplane group, this year. Employees at the St. Louis site operate in the integrated defense systems unit.

"It is amazing that after fighting against aid for Boeing workers, the president is showing up at their doorstep to praise them," said Sen. Patty Murray, D-Wash., who sponsored a provision in the war spending bill to extend unemployment benefits for aviation workers another 26 weeks. Seattle is home to a large segment of Boeing's commercial airplane operations.

On April 8, White House Office of Management and Budget Director Mitch Daniels wrote to the chairmen of the House and Senate appropriations committees to say the administration opposed the provisions because "to provide benefits for a specific industry would be unusual, unfair and potentially harmful to our national unemployment system."

The provisions were ultimately included in the bill the president signed Wednesday.

Fox News' Ian McCaleb, James Rosen and Liza Porteus and the Associated Press contributed to this report.