For the first time in more than a decade, four American military aircraft landed in Iran Sunday in a gesture between two countries more noted for acrimony than mutual aid.
The US, joining dozens of other countries in providing emergency aid after Friday's earthquake, delivered about 120,000 pounds of medical supplies and water to the nation once branded by President Bush as part of the "axis of evil."
But it is often at humanity's most trying moments that old foes are brought together in a spirit of cooperation and compassion.
"The reception was very warm," said Lt. Col. Vic Harris in a phone interview after returning to his base in Kuwait. "We worked side by side with Iranian soldiers to download the supplies. The Iranian base commander said he hoped this would be the beginning of a new relationship."
Diplomats and analysts see Washington's offer of help - and Tehran's willingness to accept it - as a test of how far each is prepared to go in publicizing a new softening of the antagonism that has marked their relationship for a quarter-century. "The Americans are starting to send in aid and it's a very positive step," says one European diplomat reached in Tehran. "Whether the momentum of goodwill is sustained is a different question."
With the death toll in the earthquake in southern Iran now estimated at more than 20,000, and up to 100,000 made homeless, the need is great.
If recent history is any guide, aid extended at such a moment can open doors that seem welded shut. Here in Turkey, a country which suffered from an equally destructive earthquake just over four years ago, generations of enmity with neighboring Greece reached a historic turning point when Greek officials sent over rescue teams. Not long after that August 1999 earthquake, Athens also suffered a major quake, and Turks in turn sent in their best emergency teams.
"We worked in great harmony with the Greeks, and of course this turned the relationship in a much more positive direction," says Nasuh Mahruki, the president of AKUT, the Turkish Search and Rescue Association, a volunteer group which assisted in the Athens earthquake and has sent teams to Iran.
After several days of rescue efforts, Mr. Mahruki recalls, the Greek president invited the Turkish teams to his official residence to thank them. "It was a great honor to be there as part of a Turkish team," he says. "Then the two countries' foreign ministers started to talk, and then the nongovernmental organizations got in contact with each other, and relations got better."
Moreover, he says, average Greeks and Turks developed a better image of the "other" - as human beings eager to help. "Even at that time, we knew that this was the beginning of a new era between Turks and Greeks," says Mahruki.
Others says that the countries' leaders were simply ready to tame decades of tensions. "If the governments want to use it as an excuse, it's a wonderful excuse," says Mehmet Ali Birand," a prominent Turkish columnist and commentator who covered the 1999 earthquakes here and in Athens. "If there is a mood in the governments" to portray that aid as a watershed, he says, that's one option - but only one of many. "The man in the street really sympathizes with those coming to help. I felt it here and I felt it in Greece," Mr. Birand says.
"The Greeks hate the Turks and they feared us, and suddenly they said, 'Look, the Turks are coming to help us.' But they bought it only because the Greeks were ready to shake hands with the Turks" at an official level, he says.
Washington has not had diplomatic relations with Iran since 1979, when students occupied the US Embassy in Tehran and held 52 Americans hostage for a 444 days. The deposition of the US-backed Shah and the ascendancy of an Islamic theocracy in his place put Washington and Tehran at odds with each other for nearly 25 years.
But analysts note that there's a small but emerging détente of late, a spin-off from the US-led war in Iraq. Iran's decision to recognize the US-appointed Iraqi Governing Council indicated a certain acquiescence to Washington's plans in Iraq. This tacit agreement with US policy in Iraq stems in part from Iran's perception that Washington shows no signs of opposing Shiite predominance in Iraq, a country that has long been ruled by its Sunni minority. Iran, the only other majority Shiite country, has become more influential in postwar Iraq and sees a pro-Iranian government there as a key to regional stability.
Concurrent with Washington and Tehran's discovery of mutual interests in Iraq, Iran has also showed its willingness to comply with demands to inspect its nuclear program. That appears to be a sign that it has no interest in upping the ante with Washington nor with Israel, the country which feels most threatened by - and would be mostly likely to launch an attack on - Iran's nuclear capabilities, notes a recent report by Stratfor, a Washington-based research service.
Though many informal channels between Iran and the US are active, official ones have not been until now. In a rare conversation, US Deputy Secretary of State Richard Armitage and Iran's permanent representative to the United Nations, Mohammad Javad Zarif, spoke by phone about Washington's offer for aid, Reuters reported.
After Iran's 1990 earthquake, which claimed 36,000 lives, Tehran was slow to accept offers of international aid. It vacillated on admitting it needed help before eventually accepting assistance from adversaries such as the US and Iraq. Iranian authorities suffered domestic criticism for not throwing open their doors sooner.
In July of 2002, the US indirectly sent some $300,000 in aid to Iran through the United Nations children's agency, UNICEF, following a smaller earthquake.
While the latest aid is appreciated, Shirzad Bozorghmehr, the deputy editor in chief of Iran News, an English-language daily in Tehran, says it would be "pure conjecture" to assume that this will turn a page in US-Iranian relations.
"These are such extreme emergency situations and I don't think politics comes into it," he says. "I don't think the US had a political motive in offering help or that Iran had a political incentive in taking this. Right now the politicians here are so preoccupied with the magnitude of the suffering."
"In short, it is a positive move on the side of the US," he says. "A gesture had been made and a gesture has been accepted."
Since the 6.6-magnitude quake on Friday, Iranian officials say that some 13,000 bodies have been recovered - and another 100,000 people are estimated to be homeless. Around 70 percent of the buildings in Bam, a city about 600 miles southeast of the capital Tehran, were flattened.
• Mike Theodoulou in Nicosia, Cyprus, contributed to this report.