The United States began taking its first steps to comply with the historic INF treaty, burning and crushing Pershing missiles outlawed in the nuclear arms reduction accord while shipping cruise missiles home from Europe for destruction.

The first of the nation's intermediate range Pershing missiles were destroyed Thursday at the Longhorn Army Ammunition Depot in Texas while 12 Soviet inspectors and Vice President George Bush watched through binoculars 1,200 feet away."We . . . are sending our INF missiles to the junk yards," Bush said. "The missile stages we destroy today are just a beginning. At the end, the levels will be equal - zero on each side. We will have destroyed an entire class of nuclear missiles. We will have relegated the INF missiles to the history books.

"We are witnessing today one of those unique moments in the career of man - a moment when the tides of history turned, that a new future dawned. It's a moment we'll be able to tell our children and grandchildren about. This is the day we began to reverse the arms race. This is the day we began to destroy the weapons of destruction."

The Intermediate Nuclear Forces Treaty, signed Dec. 8, 1987, by President Reagan and Soviet leader Mikhail Gorbachev, calls for the elimination of the entire class of missiles with ranges of 300 miles to 3,400 miles by both countries within three years.

The Soviet Union, with U.S. teams monitoring the process, started Aug. 1 with the destruction of their SS-20 triple-warhead missiles at their missile testing ground. The Soviets have so far destroyed about 100 missiles and will dispose of a total of 1,752 more on the 15th and 30th of each month over three years.

The United States started on its stockpile of 846 intermediate range missiles with the destruction of a Pershing IA Thursday, then of a Pershing II missile.

In a blast of fire and a deafening roar that shook the ground for hundreds of yards, officials at the ammunition depot ignited the missiles to burn their solid fuel. They then were crushed by machine.

Only the motor stages of the missiles and the rocket launchers were destroyed. The nuclear warheads had been removed and put into storage, said Army Secretary John Marsh, who traveled to Texas with Bush aboard Air Force Two.

After the destruction, fragments of the missile housing were given to Bush and a Soviet inspector.