Despite an intensive $4-billion drive to protect U.S. embassies against violence, at least 150 American missions abroad still fall short of security standards put in place after deadly bombings, The Associated Press has learned.

And it will cost twice that amount to replace or renovate just the most vulnerable of them, according to documents reviewed by the AP.

The push to secure U.S. diplomatic missions began in earnest after bombings of the American embassies in Kenya and Tanzania a decade ago, assaults that killed 231 people, including 12 Americans. The security effort took on new urgency after the Sept. 11, 2001, attacks in the U.S., which led to government-wide vulnerability reviews.

The results so far suggest there's a long way to go to bring all the roughly 265 U.S. embassies and consulates up to standard.

The State Department says it will need about $7.5 billion to construct new buildings at around 50 posts and $850 million for "major rehabilitation" at 40 others through 2013. The figures are contained in the department's Long-Range Overseas Buildings Plan that was sent to Congress last week.

In addition, about 60 other embassies and consulates will need to be replaced or will require substantial work by 2018, according to documents accompanying the 450-page plan, which is labeled "sensitive but unclassified" and not to be shared with foreign governments, according to officials familiar with its contents.

The long-range plan is not a formal request for funding but more like a wish-list of projects deemed critical by experts in the State Department's real estate, security and regional bureaus.

U.S. diplomatic posts fly the Stars and Stripes in capitals around the globe and are among the most high-profile overseas targets for terrorists and protesters. From Baghdad to Beijing to Belgrade, they are lightning rods for violence that has claimed the lives of dozens of diplomats over recent decades.

This year alone, embassies in Bolivia, Chad and Serbia have been attacked or overrun, not to mention the frequent barrages of rocket fire that have landed near the U.S. Embassy in Iraq.