Embassies had only low-level protection against assault

THE UNITED States has some of the most secure and well protected embassies in the world.

After a series of terrorist attacks in the Seventies, the Americans have been upgrading their 162 embassies. The need is there - a third of all attacks involving terrorists in the past year have been against American citizens or buildings.

Until now, the overseas headquarters at the Tanzanian capital in Dar es Salaam and in Nairobi, Kenya, had not been considered likely targets.

An expert on terrorism suggested yesterday that bombers, possibly from the Middle East, may have chosen the two compounds because they were considered a "soft option".

All US embassies have elaborate and extensive security arrangements ranging from bomb-proof walls and underground bunkers to hi-tech pass systems and Marine guards. Over the past 20 years, US embassies in the centres of cities considered to be in high-risk countries have been moved to the outskirts, where purpose-built compounds, often resembling fortified barracks, have been constructed.

The older and less secure embassies, which include those in Kenya and Tanzania, are much harder to defend from terrorist attack because they are often surrounded by other buildings or have limited space to install security equipment.

The most secure embassies, which include those in all Middle Eastern outposts, have reinforced walls and roofs to try to prevent terrorists firing grenades and mortars into the compounds. The walls are also designed to absorb the impact of explosions from car bombs.

An extensive system of surveillance cameras monitors all activities around and inside the compound and armed guards are posted on all the entrances. To gain access to the embassies there is a complex system of passes and barriers. No one is allowed to drive directly into the staff car park, a measure designed to ensure that a suicide bomber is not given a free run.

A special protection area, in which staff, vital records and equipment can be shielded, is usually constructed at the heart of the embassy. These self-contained zones have extra protection from bomb blasts. US embassies have five levels of security alert; from one to five, from low risk to high. A protection unit at the US State Department also trains staff in anti-terrorist procedures. Security provided by the host country can vary from excellent to almost non-existent.

Steel-reinforced bollards were installed at the US embassy in London in February.

But Professor Paul Wilkinson, chairman at the Centre for the Study of Terrorism and Political Violence at St Andrew's University, said: "American security experts and diplomats are well aware that all these physical protections are only part of the story. There's no guarantee that they will work against well co-ordinated and equipped terrorists."