The terrorist attack initiated by the Popular Assistances Committees of Hamas against southern Israel on August 18, 2011 is a pressing reminder of the unrelenting assaults by Palestinians on Israeli citizens.  Its complex military nature reinforces the case for Israel to maintain appropriate defensive structures to prevent similar attacks and suicide bombings in other parts of the country.  Case in point: the fence in the West Bank.

Considerable rhetoric has been directed against Israel for the fence.  It is understandable, as Robert Frost wrote in his poem, Mending Wall; "Something there is that doesn't love a wall, that wants it down."  Yet historical experience, such as Hadrian's Wall and the Great Wall of China, and more recently the fence between the Soviet Union and Finland and Norway, as well as manifold contemporary examples, shows how effective a good fence can be.

Barriers are very common.  They exist throughout the world, in every continent, for a variety of reasons.  Some, as in the Soviet Union and Communist countries and especially the Berlin Wall from 1961 to 1989, are created to prevent citizens from leaving a territory.  Many others exist to prevent people from entering a territory -- either a country or a particular area within it.  Some have been established to separate parties involved in a conflict or to prevent the conflict altogether, as in Belfast in 1969 and in Londonderry; Cyprus in 1974; Kuwait-Iraq in 1991; Kashmir in 2004; and the two Koreas in 1953.  Some have been set up to prevent undesirable activity, as in India to stop drug-smuggling and terrorism from Burma, or on the Kazakh-Uzbekistan border.

In Morocco, since 1995, Ceuta and Melilla, autonomous cities of Spain, have established metallic border fences to stop illegal emigration to Europe and smuggling.  Morocco, between 1980 and 1987, built a 2,700-kilometer barrier of sand and stone, the so-called Berm wall, in western Sahara to prevent attacks by the Front Polisario.  Botswana in 2003 built an electrified barbed-wire fence of 310 miles along its border with Zimbabwe.  Brunei began building a short fence along its border with Limbang.  South Africa built a barrier against Zimbabwe and Lesotho to stop illegal immigration and plunder, and also against Mozambique.  Saudi Arabia in 2004 tried to stop entrants from Yemen.  Thailand by means of a fence attempts to prevent Muslim fighters from Malaysia from crossing its borders.  Greece built a wall at the Evros River, its border with Turkey, to stop immigration by people from Muslim Asian and African countries.  The European Union has the Schengen plan to control immigration by outsiders into member countries.  China created a barrier against Hong Kong.  India has built a number of barriers to prevent illegal immigration from Bangladesh, Nepal, and Burma.  Even the United States is familiar with the issue, having built the 81-mile barrier to prevent immigration and smuggling of contraband and illegal drugs from Mexico.  While not all have been successful, many have achieved their goals.

Barriers against terrorism are also common.  The more important ones are those built by Russia against Chechnya, Pakistan against Afghanistan, Malaysia against Thailand, India against Burma, and Egypt against Gaza in 1979.  But clearly the most familiar and the one most criticized is the security fence established by Israel in the West Bank.  The multi-layered fence, including barbed wire, high walls, electronic equipment, and vehicle-barrier trenches, was the response to prior suicide bombings and terrorist attacks on Israeli citizens.  Between 2000 and July 2003, when the first part of the fence was built, 73 suicide bombings had killed nearly 300 Israelis and wounded almost 2,000.  Since 2003 the number of attacks and consequent casualties has been sharply reduced.  In 2010 the number of Israeli fatalities was nine.  Nevertheless, critics refer to the fence as a "wall"; they disregard its real purpose and accuse Israel of building it not for security but as a device to annex territory in the West Bank, to acquire water resources, and to predetermine future borders with any Palestinian entity.  Among other things they condemn Israel for imposing collective punishment on the Palestinian population by use of the fence.

Much of this critical argument rests on the opinion that the fence has been built within "Occupied Territory," not within the area of the 1949 cease-fire lines, the "Green Line," and is therefore a violation of international law.  This point of view was upheld by the advisory decision of the International Court of Justice in The Hague in 2004.  The Court called for the fence, or barrier, to be removed, explaining that Israel could not consider the lawful inhabitants of the occupied territory as a threat, and had imposed restrictions of various kinds on Palestinians in the area.  Israel could not "rely on a right of self-defense or on a state of necessity in order to preclude the wrongfulness of the construction of the wall."

As a responsible member of the international community Israel has been conscious of the criticism and the problems.  The Israeli government has reviewed and altered the route of the fence in response to stated concerns.  It modified the number of checkpoints to reduce hardships.  The Israeli Supreme Court ruled in June 2004 that a part of the fence did violate the rights of Palestinians and some rerouting took place on a number of occasions after that.

No doubt the building of the fence has had an impact on the life of Palestinians, on closure of roads, some loss of land, on access to water resources, economic life, and access to Israeli educational and health facilities.  Yet two salient points are relevant to consideration of these inconveniences.  The first is the dramatic success of the fence.  Terrorist attacks in West Bank areas where the fence has been constructed have virtually stopped; the attacks now come from Hamas terrorists in the Gaza area and near the Egyptian border, areas that do not have a similarly efficient fence.  The other is the nature of the chorus of criticism by international bodies.  Those bodies such as the Red Cross, human rights organizations, and the World Council of Churches have condemned the Israeli fence but remain conspicuously silent about other barriers throughout the world.  They, and Robert Frost too, have not accepted that Israel has demonstrated that "good fences make good neighbors."

Michael Curtis is a distinguished professor emeritus of political science at Rutgers University.