[WaterDragon]

We have to continue the SDI program. The first days of the Iraq war proved the feasibility of shooting down incoming missiles.

Once we develop it, the entire world can be brought under the shield, thus rendering nukes from rogue nations impotent. That will make nuclear weapons worthless. At last.

[dark_lord]

Once we develop it [SDI], the entire world can be brought under the shield, thus rendering nukes from rogue nations impotent. That will make nuclear weapons worthless. At last.

Nope. Nuclear weapons will then be delivered by stealth. Two examples:
(a) Delivered to seaports via submarine.
(2) Designed to be assembled from components that can be either smuggled across a border in a backpack, or hidden in shipping containers with electronic or machine parts. (The nuclear core would be backpacked in, or else slipped ashore by special forces from a sub -- the most likely scenario.)

Yes, we need SDI. But each strategy produces a counter-strategy, and I suspect the future will involve "componentized" nukes that can be assembled by specialists infiltrated into a country. Put the sucker in some suburban basement in a major metro and you are ready to go.

[TheOtherOne]

Once we develop it, the entire world can be brought under the shield, thus rendering nukes from rogue nations impotent. That will make nuclear weapons worthless. At last.

Then the issue will be suitcase nukes and the like. Once the 'missile' threat is stopped does not spell the end of nuclear threat.

[templar]

Once we develop it, the entire world can be brought under the shield, thus rendering nukes from rogue nations impotent. That will make nuclear weapons worthless.

More correctly, rendering nuclear missiles worthless. Nukes smuggled into a city by rogue governments or non-profit organizations, or delivered by FedEx or UPS would not be affected by SDI, no matter how well developed it was.

New military technology creates new military strategy. War was mostly preempted by the State during the middle ages, and now may be returning to the realm of non-State entities (Clans, ethnic groups, religious orders, etc.) as well as the official State; Or to State/non-State enterprises (aka Public/Private partnerships) to give States deniability and avoid direct conflict between armies.