By Richard Lister
BBC News, Washington
Not too many people meet the president at the White House wearing flip-flops, particularly in the freezing depths of February.
But the Dalai Lama is no ordinary visitor, and not just because of his footwear.
Despite his relatively limited political influence, the impact of the Dalai Lama's presidential face-time resounds far beyond Washington. It provides a yardstick for measuring the administration's commitment to human rights, and for assessing its willingness to stand up to China.
So his visits to the White House are minutely choreographed with the understanding that how he is received here is at least as important as what is discussed behind closed doors.
President Bill Clinton was so wary of the possible Chinese repercussions that he chose never to have a formal meeting with the Dalai Lama, opting instead to "drop by" when the Dalai Lama was meeting other US officials.
George W Bush was somewhat more welcoming, becoming the first president to be filmed in public with the Dalai Lama. The obviously warm relationship between the two men when the president gave him the Congressional Gold Medal in 2007 infuriated the Chinese.
The two men held a seemingly animated discussion
But even President Bush did not allow TV cameras into his White House meetings with the Dalai Lama, a step which would be even more antagonising to Beijing.
President Barack Obama seems to have opted for something in between those two approaches.
He met the Dalai Lama in the Map Room of the White House, avoiding the obvious symbolism of the Oval Office. A single photograph was released of the two of them, but the TV cameras were kept well away.
China condemned the meeting anyway, but that is part of the ritualised diplomatic dance that these meetings have now become
No-one expects this deliberately low-key meeting to have any real impact on US-Sino relations.
Of course, by keeping it so low-key, the president risks tarnishing his credentials as a champion of human rights.
'Worth fighting for'
There was outrage from pressure groups when the Dalai Lama came to Washington last year and the president decided not to meet him in advance of his first official trip to Beijing.
That was a clear nod to Chinese sensibilities but was inevitably condemned by those who felt human rights had been dropped down the US agenda.
After his day of meetings, I asked the Dalai Lama if he did not get frustrated having to play out this diplomatic ritual year after year with apparently so little effect.
"No!" he said, forcefully. "It doesn't matter how quickly something is achieved."
More important, he said, was that it was a cause worth fighting for, even if success was achieved "after my lifetime".
And it is clear that the Dalai Lama regards time a little differently from most people.
Douglas Paal, the senior US official who escorted the Dalai Lama into his first meeting with President George Bush in 1991, asked him if he had ever met a US president before.
The Dalai Lama laughed and said: "Neither I nor any of my 13 previous incarnations have ever met a president."
Now he can at least expect a regular invitation - with conditions. Though not about what he wears.