The millions of kilometers of pipeline crisscrossing the world have an enormous impact on the world's economy. But on a geopolitical level they are much more, from a diplomatic tool to a tempting target for terrorists.

Oil and gas are the lifeblood of the modern world. Getting them to energy hungry consumers matters, for both economic and political reasons. Any disruption in the flow of these fuels causes prices to spike and stock markets to plunge.

Pipelines play an important role in getting fuel to markets providing economic benefits for producer, importer and transit countries alike. Analysts say this makes pipelines geopolitical pawns, driving wedges between some neighbors while fostering better relations among others.

Take, for example, the proposal to build a pipeline to bring natural gas from the Caspian Sea to India. One idea is to run the pipeline from Iran through Pakistan to India.  But the U.S. government, currently at odds with Teheran over Iran's nuclear ambitions, opposes it.

Secretary of State Condoleezza Rice made that clear during a joint appearance before reporters with Indian Foreign Minister Natwar Singh.

Secretary of State Condoleezza Rice

"We have communicated to the Indian government our concerns about gas pipeline cooperation between Iran and India.  I think our ambassador has made statements in that regard.  And so those concerns ARE well-known to the Indian government," says Dr. Rice.

India does not share those concerns. 

Any pipeline bringing gas to India would also have to pass through Pakistan, India's neighbor and archrival. Pakistani Prime Minister Shaukat Aziz believes the pipeline would do much to heal the longstanding Indo-Pakistani rift.

But, as Gal Luft, director of the Institute for Analysis of Global Security, points out, the tangible economic benefits that transit countries like Pakistan can enjoy also play into the political equations.

Gal Luft, Director of the Institute for Analysis of Global Security

"A lot of these countries are in desperate need for energy, they need oil and gas. And if you had a pipeline going through your territory you can derive energy out of it.  The other incentive is to get the transit fee. 40 or 50 cents per barrel of oil is a lot of money, it adds up. So that is a source of income for some very poor countries," says Gal Luft.

The same factors that make pipelines attractive economically also make them tempting targets for terrorists. Gal Luft says the vulnerability of pipelines became apparent after the terrorist attacks of September 11, 2001

"Since 9/11 it has become increasingly apparent that terrorists see oil as the Achilles heel of the west. All you need to blow up a pipeline is a couple of pounds of explosives and you blow the pipe and you take the pipeline out of operation for a number of weeks," says Gal Luft.

Pipelines are generally built above ground and in the open, making them especially vulnerable to sabotage.  Nowhere has this become more apparent, say analysts, than in Iraq where attacks take place with alarming frequency. Without the flow of oil, you can't export and earn hard currency. This in turn hampers reconstruction.

Guarding against pipeline sabotage is an expensive and labor-intensive job.  There simply aren't enough troops to protect every stretch of a pipeline, making sabotage almost inevitable.  

Gal Luft says the best safeguard is to have top-notch repair crews on standby to ensure that any damage is quickly repaired.

"So to shorten the time of the disruption by making sure there are enough teams on the ground by making sure there's enough spare parts on the shelf and making sure that instead of the pipeline being out of operation for a number of weeks, its only out of operation for a matter of hours or a number of days," says Gal Luft.

With the energy demands of the world only going up, keeping the flow of oil steady and predictable has never been more important for the global economy.