Warfare in the 21st century has changed. The tragic events of Sept. 11, 2001, proved new enemies have arisen that threaten the safety and security of peace-loving nations.

It’s time our country re-evaluate the manner in which our military conducts its operations. To this end, it is necessary to support research into new weapons systems, including low-yield and bunker-busting nuclear warheads.

As we look at future threats, we know that nations are beginning to locate much of their critical defense infrastructure underground in hardened bunkers in an attempt to minimize the devastating

impact of our bombing campaigns. It is time to look at how the United States will be able to destroy these targets should a future engagement require us to act. In fact, I believe it would be foolish and irresponsible not to consider all our options.

The Pentagon and other military planners have done the prudent thing by requesting that Congress allow research on the potential use of low-yield nuclear weapons for a specific military purpose.

As we have seen in Afghanistan, Iraq and North Korea, the enemy has gone underground — not only to hide their forces, but to hide weaponry, to potentially build chemical or biological weapons facilities and to develop nuclear weapons.

The Senate, in a bipartisan fashion, voted to allow research related to the feasibility of creating a delivery vehicle capable of reaching hardened buried targets, and to allow our scientists to think about and model low-yield nuclear weapons that might be used to counter a threat to our nation.

I understand and appreciate arguments that are made on the other side of this issue, that while we are asking other nations to not develop nuclear weapons, we are looking at future weapons designs. However, the first priority of the federal government is to protect the American people. [IMGCAP(1)]

It is important to understand two facts about lifting the restrictions on this research. First, the RNEP (Robust Earth Nuclear Penetrator) program, as proposed by the Pentagon, does not call for the development of any new type of nuclear warhead. Second, the United States already has in its inventory weapons that could be defined as low yield.

From the previous Persian Gulf War to Operation Iraqi Freedom, we have seen how the military has modernized and transformed itself. In the first Gulf War only about 10 percent of the weapons used were precision-guided munitions. That changed to the point where 90 percent of the weapons used in Operation Iraqi Freedom were precision guided. I argue that the modernization effort, keeping the technological edge, saved a lot of American and Iraqi lives.

This is a dramatic moment in our nation’s history. We have upgraded the threat level to orange. Al Qaeda is still alive. They are on the run, but they have the ability to hurt people. They desire nuclear weapons.

There are a lot of rogue states that are going to try to pursue a nuclear weapon, or fissile materials, and they will most likely be successful. People are going to continue to enhance their biological and nuclear weapons ability.

To stop research on a potential weapon that could destroy a terrorist group or prevent a rogue nation from creating a chemical or biological capacity that is deep underground is illogical — not thinking about the future, not thinking about these technologies and weapons doesn’t do anything to stop the spread of nuclear weapons; it just takes our options off the table.

It is a reality that the enemies of today and tomorrow will go underground. They will go deep into the earth, and they will have laboratories and research facilities available to them to develop weapons of mass destruction.

Our conventional weapons may not be able to destroy the enemy’s chemical or biological factory or nuclear weapons program. It may also take too long to amass and transport the necessary ground forces to go in on and overtake the facility.

It is our responsibility to at least look at the possibility of having a weapons mix in the future that protects us from the evil that exists today and in the future. We must not limit our ability to research and develop a weapon that counteracts that threat. To take the research component off the table and not even plan for that possibility is irresponsible.

History will judge us poorly if we do not listen to what I believe to be a real threat and try to at least talk about and develop a counteraction to that threat for the future. To continue the ban on this research would tie the hands of the American military in looking at weapons systems to combat a real threat at a time when the threats we face are growing, not lessening.

We are not talking about deploying a weapon. We are talking about researching weapons that may save lives in the future. That’s certainly an endeavor worth exploring.

Sen. Lindsey Graham (R-S.C.) is a member of the Armed Services Committee.