Patrick Cockburn: This ugly fortress proves the US does not expect affection

The US embassy in the Yemeni capital Sanaa, which has just closed its doors because of the al-Qa'ida threat, is a spectacularly ugly building that has been designed as a fortress to withstand a military assault.

It is easy to understand why the State Department may be feeling nervous about the embassy's security. It was the target of two vehicles packed with explosives driven by suicide bombers in September 2008 in an attack in which 19 people were killed, one of them an American woman. At the start of the US invasion in Iraq in 2003, demonstrators tried to storm it and two were killed. Last year three mortar bombs were fired at the building, all of which missed and hit a girl's school instead, killing a security guard.

The architecture is the fruit of security reviews that see embassies as concrete bunkers built to withstand attack in a hostile land and not as a centre for spreading goodwill towards America. This is hardly surprising considering the fate of US embassies from Tehran to Beirut. The closure of the embassy may also reflect realism among US diplomats in Sanaa over the ability of the central government to defend them despite proffered aid from the US and an American-British Yemeni counter-terrorism force.

When I visited the embassy some years ago, staff wrestled with heavy internal doors, which that looked as if they had come from the vaults of a bank, and elaborate security measures which seemed to paralyse its functioning. It seemed a gloomy place to live and one from which it would be almost impossible to work.

The US and Britain may come to regret intervening in Yemen, which is very much an Arab Afghanistan with state authority contested in many parts of the country. The establishment of an anti-terrorism squad of foreign trained Yemeni security men will be a double-edged sword as the Yemeni government will seek to portray its many enemies, be they Shia insurgents in the north or secessionists in the south, as allies of al-Qa'ida.

The closure of the US embassy also underlines how vulnerable these facilities are in the age of the suicide bomber. To defend them at all means, as in Baghdad, turns them into a heavily defended foreign enclave which is resented locally and becomes a physical symbol of imperialist designs.