The final part of the equation for any initial attack on Afghanistan is how strong a coalition the US will be able to build in the region. Many of the region's powers find themselves in a difficult position due to complicated local relationships and the internal tensions within their own populations. So while the US may use forces based in Saudi Arabia, it does not necessarily follow that it would consider itself a partner in a coalition in anything similar to that assembled during the Gulf War. Equally, there is no chance that Iran would consider itself a US ally but Washington would consider its continuing neutrality a vital diplomatic and strategic gesture. The critical factor is how these relationships may change over the coming months. A sustained military assault on Afghanistan would almost certainly unsettle public opinion in some parts of the region - the question is how this would affect the policy of the respective neighbours.