DESPITE MANY SINCERE attempts to control the growth of nuclear arsenals, they have continued to grow. Time and time again, the Soviet Union has used the facade of negotiations while continuing its relentless military buildup.

President Reagan has consistently expressed his concern directly and without equivocation. That concern is particularly acute because the president has characterized the Soviet Union as a state with no respect for traditional moral values and ethical norms. Some commentators pointedly criticized the president for having the courage to express this reality to the American people. What do those commentators say now?

The sickening display of Soviet barbarism in the Korean Air Lines massacre shocked us all. But this dramatically brutal act is consistent with the behavior of a government that continues to terrorize and murder the Afghan people, using chemical weapons on Afghan villages, and which sponsors the repression of the entire Polish nation.

You see, one of the real tragedies of the KAL atrocity is that it is not, as some suggest, an unexplainable departure from Soviet attitude, Soviet policy and Soviet strategy. The Soviet leadership has stated that it would commit another massacre if another civilian airliner entered its airspace, despite the outrage expressed by the entire civilized world. They appear unaffected.

The Soviet strategy in the aftermath of the incident has been gross intimidation and falsehood. The sad thing is that in some quarters, their very crudity has been effective. People have questioned clear evidence, or have been diverted from it. Some have been seduced or intimidated by Soviet attempts to mislead, as if desperately searching for a fig leaf to cover Soviet nakedness.

The Soviets feel no need for a fig leaf. They have brazened it out, without remorse or apology, without any humility whatsoever. The Soviets ask the world to believe the unbelievable: that an innocent, stray plane was on a spy mission in the dark of night over Soviet islands. The absolute and incontrovertible fact is that KAL 007 was not on an intelligence gathering mission of any kind. On the other hand, the Soviets and their surrogates do use passenger aircraft for espionage purposes and have overflown the United States on spying missions. Neither our nor any government which holds life precious would consider mass murder as a response.

In the past when the Soviets have committed their most egregious crimes, they and their apologists both here and abroad have attempted to somehow blame such incidents on the United States or its allies. In this case, they are well embarked upon just such a mission and, we believe, they will take further initiatives to cover up. We must anticipate the Soviets will fabricate so-called "newly discovered evidence" to prove the spy plane thesis.

Already, they are saying that the airline massacre was the result of strained U.S.-Soviet relations. They will, of course, blame that relationship on our government's actions and suggest that a summit be called to reach "greater understanding."

We are also seeing disinformation about Soviet paranoia -- as if their fears of nonexistent external threats are either rational and legitimate on the one hand, or irrational on the other, and therefore somehow beyond their responsibility. I heard those arguments many times during my years on the bench. We should not allow the "self-defense" or the "insanity" plea to exonerate them.

Let us keep to the essential facts: The Soviet military government, with no concern for human life, tracked an unarmed, innocent civilian airliner with 269 innocent people on board for 21/2 hours. Then, as it was leaving or had just left Soviet air space -- there is a 60-second question mark there -- they mortally wounded that airplane, and its precious cargo. They show no remorse, make no restitution, and threaten similar action in the future. No wonder U.S.-Soviet relation are not good.

It is against this background that the president confronts the greatest challenge of our time -- rebuilding our national defense and pursuing a lasting peace. Our purposes are straightforward -- to protect our country, to reduce the risk of war and, ultimately, to reduce dramatically the level of nuclear weapons.

The importance of these objectives demands that we stay on the course we have set despite the profound tragedy over the Sea of Japan. It means that our critical negotiations with the Soviet Union must proceed. A response motivated by revenge would not bring about a safer world. It also means we must vigorously pursue the three interdependent keys to our country's security: modernization to maintain state-of-the-art readiness for our entire triad of nuclear forces; deterrence to continue to make clear to the Soviet Union that aggression would never pay and progress in arms reductions to move from a balance of terror toward a stable nuclear posture at reduced, verifiable levels.

Progress in each of these areas has not been easy. In fact, it has been painfully slow. Nevertheless, an important and encouraging development has taken place during the past six months. Our political process has finally forged a bipartisan consensus, albeit still tender, that has united us in our common search for peace and security. And this consensus, which must be strengthened and then sustained, is an essential component of the president's vision of a safer America and a more peaceful world.

Too many people have worked too long and too hard -- and with a genuine spirit of compromise -- to turn back now. No longer can the skeptics of the president's national security program -- indeed, America's program -- justify their position on the hope that continued American self-restraint will bring about fair, equitable and verifiable arms reduction agreements. No, it won't happen that way. But if we display determination and willingness to pay the price to ensure our safety and freedom now and for future generations, then there is solid chance for success.