Analysing moves to expand SA's mobile military capacities, Business Day has said this raises "questions about the heavy investment in naval power in the arms acquisition package".

This landward approach ignores the maritime dimension to SA's security.

Any coastal state needs a defence force and a navy. If a navy is good enough at war fighting, it may also make and keep the peace. It may prevent piracy; theft of fish stocks; the death of merchant mariners by drowning or illness; and it may prevent or diminish ecological disasters.

If it is good enough at war, a navy may educate and train young adults to high standards of technological skill and civic duty. If a navy can not fight a war well, there will be no peace. This is the paradox of the navy.

SA is twice the size of Texas. It has an even bigger coastline, and a vastly bigger economic exclusion zone. SA has better, more enviable natural resources than Texas, oil excepted. It has three times the population.

If this population were to be well educated, SA would be an economic nirvana.

Therefore the bulk of government's budget is rightly devoted to education, and health, water, electrification, sanitation, roads, clinics, houses, and information systems. Government has delivery problems, but the priorities are right.

It would be criminal to overspend on defence and the navy, when children starve, and mothers can not read and write. Yet it would be equally criminal to underspend on defence and the navy. SA owns the 20th largest economy on earth, measured by gross domestic product at purchasing power parity.

Enviable natural resources can not be left undefended, or we will be doing the envying and someone else will be doing the enjoying. On the one hand, the defence budget and the navy must not be too big, or our children will starve. On the other hand, the defence budget and the navy must not be too small, or our country will be stolen. In mathematics this is called optimisation.

SA has been a modern state for more than a century. SA is the largest economy in Africa. A large modern state needs defence and a navy that is equally modern, and equally large.

SA was reconquered from the sea 100 years ago. The Anglo Boer War was a modern land war, of rifles, pom poms, machine guns, searchlights, Krupp Long Toms, and armoured trains. It was won because Kitchener laid down "all the barbed wire in the world".

But it was also won because the Royal Navy could deliver to Table Bay more than half-a-million invading soldiers from the four corners of the earth.

That seaborne invasion had mixed results. The absolute losers were SA's blacks. Without that war, we would not be a modern industrial state, but it reduced the wage paid to black gold miners by a third. It continued segregation. It paved the way for apartheid. The Anglo Boer War reconquered black South Africans, and turned them into Helots for a century. That war came from the sea.

The price paid by black SA for not having a navy was a century of servitude. The new nonracial SA need not repeat the error. It needs a navy big enough to make any aggressor think twice.

Hundreds of cargo vessels were torpedoed and sunk off our coasts in the Second World War. Both the First and Second World War saw our soldiers able to make a difference, for the general good of the world, thousands of miles from home, because they could get there by sea.

Sealift is still the most efficient and flexible way of moving heavy armies long distances. If we wish to play our part in keeping the peace, or in making just war, we need a navy.

SA needs a navy because more than 95% of its trade goes by sea. Durban is the busiest port on the continent, and hugely vulnerable. SA needs a navy because it has so few ports, and its lines of communication are dangerously concentrated.

The Southern African Development Community (SADC) states cover 3,7-million square miles. SADC laws make each state responsible for the other, particularly in the face of coups by junior officers. What if we need to come to the assistance of our neighbours? We lack strategic reach, as a matter of policy.

Except for the navy. Small numbers of troops and air cover can be airlifted into a trouble spot. If the railway happens to go that way, larger volumes can be moved. But for many SADC states, especially those with coastal cities, seaborne operations are ideal.

The stability of SADC depends upon its richest member, SA, playing a role that matches its financial size.

Our own economic future may in part depend on perceptions of the security of the rest of SADC. It may be in our own economic interest that we beef up our strategic reach through the navy.

Prof Christie is Dean of Research at the University of the Western Cape.

Enviable natural resources can not be left undefended.

With acknowledgements to Renfrew Christie and Business Day.