There are several areas of this planet permanently damaged by pollution from weapons of war. Some modern weapons have effects greater than intended.
So-called Depleted Uranium has been used to make shells heavier and more penetrating. Its manufacturers claim it has no radioactive effects. However in the places it has been used: Iraq and Kuwait (1991); Kosovo and Serbia 1999 there have been rises in the rates of cancers and malformed births. Is this caused by the residual radioactivity or by chemical effects? No-one knows as insufficient research has been done.

There have been reports of a rising rate of birth defects in Afghanistan after the use of Depleted Uranium in the original attack on the country to expel the Taliban government.

So far the military have not admitted responsibility.

The same is true of Fallujah in Iraq where there are reports (March 2010) of increased birth defects. Depleted Uranium may be suspected.

Agent Orange
The US sprayed defoliating agents over Vietnam, Laos and Cambodia during the Vietnam war. There has been a legacy in that area of birth malformations and high rates of cancer, caused by the TCCD (Dioxin) which was a contaminant of the main chemical - a hormone weedkiller. The purpose was to kill the rain forest, which only slowly grows back.
Among the sufferers are many of the US forces who delivered the chemicals, ate fish and animals from the affected areas, swam in the rivers and lakes.
Cluster bombs and Mines
Although some of the major powers have agreed not to use landmines, the US and Britain still use cluster bombs: a single bomb containing many small bombs which are released on the first explosion. Many of these small bomblets do not explode at once but remain unexploded like landmines.They continue to endanger lives.
Children tend to pick them up. They can be active for tens of years after the conflict. Mines can remain for many years, blowing off people's feet and legs.

Christopher Hitchens - Arguably

Arguably: Essays by Christopher Hitchens: Selected Essays

Includes an essay on the effects of "agent orange"

1) Can the military be forced not to use chemicals and other substances that have long-term health effects?

The military are notoriously resistant to any control.

2) Can some of the weapons of the past ever be cleared up?

So far the TCCD dropped on Vietnam seems to be there for ever. Should the land be abandoned? Where would the people go? Is there serious research into a way of removing this substance? Could there be a microbial method of digesting it? We should all hope so, but so far there are few indications of success.

There is no known method of recovering the depleted uranium from shell fragments and dust. If found on the surface it can be gathered up and buried in deep pits, but only some of it can be treated in this way.