For now, the tables certainly seemed to have turned. Adia has rescued a flagship US financial institution with a loan that can be converted into 4.9 per cent of its shares. The investment will provide Citigroup, which has lost billions of dollars in the sub-prime crisis, with a much-needed cash injection.

The US has not always been so receptive to Arab investors. There was political uproar in Washington when Dubai ports operator DP World tried to buy P&O's US assets in 2006.

This time around, Adia has been seen not as a predator but as a rescuer. And the deal counters critics, many of them also in the US, who have railed against sovereign wealth funds, seeing them as murky, unaccountable investors.

But ultimately, the Gulf and the rest of the world needs a healthy US economy. The longer the US is sickly, the greater the chances that it could pull others down with it. Not least China, which relies on the US as a vital export market, and which the Gulf relies on to buy its oil.

Interest rates of 11 per cent are not in Citigroup's long-term interest, but nor are they in the Middle East's.