BBC News, Washington
Senior US government officials have called on Spaniards not to let the bomb attacks in Madrid deter them from the fight against terrorism.
The majority of Spaniards opposed the deployment of troops to Iraq
The appeals came just a few days before the first anniversary of the war in Iraq.
The Spanish government was a key ally in the war in Iraq, but most Spanish people were opposed.
Indications have emerged that the Madrid attack may have been in revenge for Spain's involvement in Iraq.
But the Bush administration says it hopes Spain will not back down.
Secretary of State Colin Powell, Defence Secretary Donald Rumsfeld and National Security Adviser Condoleezza Rice all appeared on American television shows to defend US foreign policy.
Mr Rumsfeld said to backing down would be like feeding an alligator in the hope that it will eat you last.
Ms Rice said the attack in Spain was just more evidence that terrorists were trying to intimidate those fighting them; but she said the US and its allies could defeat terrorism if they took tough and aggressive action.
Mr Powell said even if a new Spanish government is chosen in the election there, it too would realize it had to keep its forces in Iraq with a United Nations mandate.
Spain's Popular Party government was ousted at the polls hours after Mr Powell's comments.
All three said they did not yet know whether the Basque separatist group, Eta, or al-Qaeda was behind the attacks in Madrid, but that they were confident the Spanish government would explore all avenues to discover the truth.