Airline security measures introduced by Washington after a failed attempt to blow up a flight on Christmas Day risk backfiring because they have angered important US partners in the fight against al Qaeda.
Saudi Arabia, Algeria and Nigeria have voiced their displeasure at their inclusion on a 14-country list where passengers departing for the United States are to be subject to especially rigorous pre-flight screening.
None of them have said publicly they will scale back security cooperation with the United States in response, but relations have been left frayed and Washington was worried enough to assign a senior diplomat to try to repair the damage.
"The United States is behaving like a bull in a china shop," said Mohamed Lagab, an Algerian lecturer in political science who has close ties to his country's government.
Washington announced the new security measures soon after Umar Farouk Abdulmutallab, a Nigerian man described by US officials as an al Qaeda operative, is alleged to have tried to detonate explosives hidden in his underwear on a December 25 flight as it approached the US city of Detroit.
The 14 countries on Washington's list are Cuba, Iran, Syria, Sudan, Afghanistan, Algeria, Iraq, Lebanon, Libya, Nigeria, Pakistan, Saudi Arabia, Somalia and Yemen.
Several independent analysts have said the list does little to plug the security gaps exposed by the bomb attempt. Meanwhile for some US allies, inclusion on what they perceive as a terrorism blacklist has been a shock and an insult.
Saudi Arabia's Foreign Ministry has sent a request to the US State Department to clarify the move, Western diplomats and a Saudi security source said.
The world's largest petroleum exporter, Saudi Arabia has almost entirely stamped out a wave of domestic al Qaeda violence that began six years ago.
"This is probably the first measure by the Obama administration in its global campaign against terrorism. It is a very disappointing measure for us, because what we were expecting was a deeper and more efficient cooperation," the Saudi security source said.
In Nigeria, Information Minister Dora Akunyili said her country's inclusion was "unfair". She warned that bilateral relations between Nigeria and the United States, purchaser of 45 percent of its oil exports, could be at risk.
In Algeria, Foreign Minister Mourad Medelci summoned the US ambassador and said Algeria's inclusion in the list was "unfortunate, unjustified and discriminatory."
There was also grass-roots anger in Algeria, a North African oil and gas producer where security forces have made progress in clamping down on an al Qaeda-linked insurgency.
"I don't think we deserve this," said Farouk Guettouche, a 44-year-old unemployed man. "We're not Afghanistan."
US Deputy Assistant Secretary of State Janet Sanderson flew to Algiers last week for what she said afterwards were "frank" talks focusing on the security list. She said she was also having consultations on the issue with other US allies.
"Let me assure you that my government has heard you," she told reporters in Algiers. "What we are trying to do is to create a system that responds to the ever-changing conditions that the terrorists seem to be able to exploit."
Washington is anxious not to hurt diplomatic ties because important security cooperation is at stake, especially with Saudi Arabia and Algeria, two countries in the front line of the battle against al Qaeda.
The United States is relying on Saudi assistance to help prevent al Qaeda expanding its foothold in neighbouring Yemen — the focus of intense US attention after the Yemeni arm of Osama bin Laden's network claimed responsibility for the Christmas Day bomb plot.
Turki al-Sahil, who covers diplomatic and security issues at Saudi Arabia's Asharq al-Awsat newspaper, said security cooperation with Washington would bounce back. "Saudi Arabia and US strategic interests are bigger than this," he said.
Security ties with Algeria are less robust. The United States needs its help to contain the spread of al Qaeda in the vast and poorly policed Sahara desert, but Algeria's government is ambivalent about a growing US role in the region.
"The Americans' interests and their security are at stake," Algeria's Liberte newspaper wrote about the list. "They should remedy their mistake and by doing so encourage Algeria to continue its implacable fight against terrorism."