The US president says the deaths of 15 soldiers in Sunday's attack on a helicopter in Iraq will not deter American efforts there.
Soldiers combed the crash site for survivors
He spoke as reports came through of three people killed in a blast in the holy city of Karbala and as explosions were heard near the US headquarters in Baghdad.
"The enemy in Iraq believes America will run. That's why they're willing to kill innocent civilians, relief workers, coalition troops. America will never run," President George W Bush said.
On Monday evening, the US Senate voted through the president's $87.5bn package for reconstruction for Iraq and Afghanistan.
It is the US's most expensive and ambitious effort since the Marshall Plan to rehabilitate Europe after World War II.
Bowing to Mr Bush's demands, the lawmakers provided all of the nearly $20bn reconstruction money for Iraq as a no-strings grant.
Earlier a number of Republicans joined Democrats in advocating that at
least half of the rebuilding money be in the form of loans.
Senators had defied the president by voting to convert half of a $20bn aid package to rebuild Iraq into a loan.
MAJOR POST-WAR ATTACKS
27 Oct: 36 killed in co-ordinated suicide attacks on Red Cross HQ and police stations in Baghdad
29 Aug: Shia Muslim cleric Ayatollah Mohammed Baqr al-Hakim among 80 killed in bombing in Najaf
19 Aug: UN special representative among 22 killed in attack on UN HQ in Baghdad
But the White House had threatened to veto the entire bill if it required any repayment, which it argued would undermine efforts to stabilise Iraq, prolong the US occupation and
burden Iraq with more debt.
In the wake of the helicopter attack, the Senate backed the measure with a simple voice vote, instead of a formal roll call.
The huge transport helicopter which was downed near Falluja had been carrying troops home for rest and recreation.
BBC correspondent in Washington Kathy Kay says Mr Bush's now familiar message of staying the course has taken on new urgency.
An opinion poll over the weekend shows that for the first time a slim majority of Americans now disapprove of the president's handling of the war.
Every attack on America soldiers erodes that support even further and increases pressure on the White House to bring the troops home, she says.
Some senators have welcomed the approval of the reconstruction fund.
"Our men and women in uniform face
life-threatening obstacles every day, and are counting on us to
provide them with the resources they need to get the job done," said Ted Stevens, the Republican chairman of the Senate's appropriations committee.
"This supplemental will provide the equipment, fuel, ammunition
and pay our forces need and deserve as they continue their tasks in
Iraq, Afghanistan and other locations," he said.
However Senator Robert Byrd of West Virginia called the bill "a
monument to failure" that contradicted the White House's assurances last spring that Iraq would finance most of its rebuilding.