Saudi Arabia has rejected accusations in a US congressional report that it assisted hijackers in carrying out the 11 September attacks in America.
BBC security correspondent Frank Gardner assesses the report's wider implications.
What are the accusations against Saudi Arabia?
We do not know specifically what the charges are because 28 pages of the report have not been made public. It is evidently extremely sensitive material.
But judging from what US senators and certain people in Washington are saying, Saudi Arabia effectively helped the hijackers to carry out the 9/11 attacks against America. It is a charge which the Saudi Government strongly rejects.
Are they justified?
We would have to see these 28 pages to know if they are justified. The suspicion has long been in both the US and British intelligence services that Saudi Arabia was in some way complicit in the attacks of 9/11 because it didn't do enough to stem the flow of money and assistance to al-Qaeda.
But it is much more specific than that. There are links between elements of the Saudi ruling family and certain Islamic causes, some of which have ended up having ties with al-Qaeda.
It is very difficult to say the leaders of the Saudi ruling family are responsible for 9/11. Some in Washington would like to say they are. But it is more a case of what they did not do than what they did.
What is the Saudi reaction to this?
There has not yet been an official reaction to this from Saudi Arabia. But there has been strong reaction from the Saudi ambassador in Washington who is reflecting official policy, saying they strongly reject any criticism that Saudi Arabia was responsible for 9/11.
There has been a large element of denial on the part of the Saudi Government. The Saudi interior minister claimed for months that no Saudis were involved in the 9/11 hijacking. Until quite recently he claimed there was no al-Qaeda in Saudi Arabia itself.
Now that it has been established that there are terror cells in Saudi linked to al-Qaeda, the Saudis are doing a huge amount to cooperate with the Americans.
But it is engendering a certain amount of ill-feeling amongst ordinary Saudis who are getting fed up with all the checkpoints, searches and security precautions which they feel are being imposed on Saudi at the behest of Washington.
How will the report affect relations between the two countries?
The report will annoy Saudi officials although they will respect the fact that the Americans have chosen not to reveal those 28 pages which would be even more embarrassing for the Saudi Government.
As far as ordinary Saudis are concerned, they will probably shrug it off as American prejudice.
Many Saudis still believe in their hearts that Israel was in some way responsible for 9/11 - an Israeli plot to try to discredit the Arabs and make Americans go to war against Muslims.
Is Saudi Arabia making progress in its fight against domestic terror?
They have had a lot of breakthroughs. They have killed or captured a number of the leading members of various terror cells that they have been looking for.
Having said that, Saudis tell me that for every one killed there are plenty of others willing to take his place - the Hydra's head idea.
It is not as simple as saying, "Do you support Al-Qaeda?" There are parts of Saudi society which are immensely impoverished.
There is a feeling of enormous fiscal inequality - the huge layer of princes at the top of the country who lead a gilded life and an ever increasing public who live on or below the poverty level.
The wealth gap is widening and without political representation that is going to be a problem which could eventually lead to an explosion.