The Pentagon, in a reassessment that would reverse 20 years of Army policy, is questioning the need for thousands of short-range, battlefield nuclear weapons that it has deployed or plans to build, according to top Defense Department officials.

The review reflects a realization that the older weapons would be difficult to use in wartime and that deploying the newer ones would create severe political problems.

The review comes as the North Atlantic Treaty Organization is seeking to reduce the approximately 6,000 U.S. nuclear weapons in Europe by at least 572 warheads in conjunction with deployment, planned to start in December, of that number of longer-range Pershing II and ground-launched cruise missiles.

There also is growing public criticism within the United States and in western Europe of short-range nuclear systems.

A report to be released soon by NATO's interparliamentary arm, the North Atlantic Assembly, calls for such reductions, saying "many of the systems lack accuracy . . . the warhead yields are too large for battlefield use . . . most have extremely short ranges which would mean use on or near 'own territory' . . . and the warhead storage sites are vulnerable to preemptive attack."

The report said there is "growing realization that the present tactical nuclear systems are effectively unusable and therefore NATO has little to lose and much to gain, particularly in a political sense, by reducing if not eliminating them."

In one section, the report disclosed that after 20 years, the western alliance "has not yet managed to agree on guidelines for the follow-on use of nuclear weapons if a first attempt to communicate NATO's intentions through a controlled demonstrative use did not succeed in persuading the adversary to halt hostilities."

Sen. Joseph R. Biden Jr. (D-Del.), chairman of the NATO group that did the study, is circulating a letter to President Reagan for signatures by his Senate colleagues. The letter supports reduction of battlefield warheads.

The immediate issues for Pentagon officials are whether the Army will go ahead with more than 1,000 new, 155-mm neutron artillery shells or develop a nuclear warhead for a proposed new battlefield missile, air- and ground-launched, with a range of 150 to 250 miles.

The latter is a joint undertaking with the Air Force.

Also involved in the Pentagon review is how many of about 2,000 older U.S. nuclear artillery shells and more than 1,000 nuclear antiaircraft and atomic demolition munitions with troops in western Europe will be returned to the United States and dismantled.

An Army spokesman said the service would not discuss battlefield weapons.

Last year, Congress turned down initial production money for the 155-mm shells, but $63 million has been included in the fiscal 1984 Pentagon budget now on Capitol Hill.

According to government sources, some Pentagon officials are prepared to drop the request for the shell because of its multibillion-dollar cost, doubts that it can be deployed in Europe in the face of political opposition and unavailablity until at least 1986.

The change in attitude toward short-range nuclear weapons is illustrated in previously classified testimony by Gen. Bernard Rogers, NATO commander and former Army chief of staff, before the Senate Armed Services Committee last year.

Rogers noted that NATO, far behind the Soviets in long-range nuclear missiles, already has "about a 3-to-1 advantage for theater nuclear weapons with a range less than 150 kilometers." That advantage is composed primarily of several thousand nuclear artillery shells, a type the Soviets have not built in any numbers.

During the hearing, another Army general described these older 8-inch and 155-mm shells, many of which are 20 years old, as having "inadequate ranges and inaccurate fuzes." The 8-inch shell, he said, "requires time-consuming field assembly" and requires firing of a spotter shell before the nuclear round can be fired.

As to the newer, eight-inch neutron shell being built, Rogers said, "I can get the same effects from the weapons we have now as I can get with the neutron weapon warhead. The only trouble is that it can't be used in as close proximity to our own troops because of the blast and thermal damage of those that we have."

Asked to choose between new neutron shells or new chemical weapons, Rogers responded: "It is more important to me to have the modern adequate chemical capability to retaliate than the neutron weapon."

The administration has asked Congress to approve production funds for a new generation of chemical shells and bombs.

That is a sharply different approach to neutron battlefield weapons, which fewer than six years ago were seen as the major weapon system to defend NATO troops against Soviet tanks.

Rogers and the Army now are stressing a new approach against a Soviet invasion, with emphasis on hitting second-echelon enemy forces well behind the forward lines with conventional rather than nuclear weapons.

The NATO review is being conducted by a subcommittee called the "high-level group" and chaired by assistant defense secretary Richard N. Perle.

The group reportedly has produced interim recommendations for nuclear warhead reductions to accompany deployment of the Pershing II and cruise missiles.

Those findings will be presented to the upcoming meeting in Lisbon of NATO's nuclear planning group. No public disclosure of those findings is expected, but Pentagon sources said that any nuclear warhead reductions would be widely publicized.

Of U.S. warheads currently deployed in Europe, more than 2,000 are old 8-inch and 155-mm artillery shells, and another 600 are warheads for the Lance missile. At least 500 are atomic demolition munitions, nuclear devices to be planted as mines on main invasion routes from eastern Europe into West Germany. About 600 are nuclear warheads for the Nike Hercules, an antiaircraft weapon no longer deployed in the United States.

The remaining nuclear weapons are air-delivered bombs and assorted devices such as anti-submarine bombs and warheads for the Honest John missile, the launcher no longer maintained by the U.S. Army but still in the inventory of Italian and Dutch troops.

The controversial neutron replacements for the old 8-inch artillery shells are being produced, at more than $1 million per shell, but are being stockpiled in the United States. Meanwhile, the old 8-inch nuclear shells, described as unusable during the debate about the neutron weapons, remain in Europe.

About 300 neutron Lance missile warheads also are being produced, at almost $3 million per warhead, according to one industry source. They, too, are being stockpiled here.

Over the last year, the Army has withdrawn some old atomic munitions and warheads for the Nike Hercules, but without public notice.

Perle's NATO group is expected to recommend that remaining Nike Hercules warheads be withdrawn, in part because the antiaircraft system is to be replaced by the Patriot, a new electronic system.

Some older artillery shells also are candidates for removal, according to sources.