President Carter, who during his election campaign called for cutting the Pentagon budget, yesterday asked Congress to continue his predecessor's expansionary policy in national defense.

After allowing for inflation, Carter's request for a record high $126 billion in spending authority for fiscal 1979 represents a 2.3 per cent "real" increase, continuing the upward trend started in the Nixon-Ford administration.

In terms of the $125.6 billion in spending authority he wants from Congress and the $115.2 billion the President figures will actually be spent within fiscal 1979, the Carter budget represents real increases of 3.4 per cent and 3.5 per cent, respectively, over former President Ford's last defense budget.

Defense Secretary Harold Brown insisted at a Pentagon press conference Saturday that Carter's first defense budget fulfills the president's campaign pledges to cut Pentagon spending between $5 billion and $7 billion annually.

"The numbers speak for themselves," Brown said. The Ford administration's fiscal 1979 projections for the Pentagon budget were $8.4 billion higher for total obligations and $5.6 billion higher in spending than Carter's budget.

Campaign pledges and arithemetic aside, Carter's first military budget shows that he wants to spend more money on non-nuclear land forces for NATO, rethink what kind of Navy should be built for the future and stick with the nuclear strategic forces already deployes rather than plunge ahead with new ones.

Constraint marks the budget in the strategic area, with the MX nuclear blockbuster land missile accelerating only slightly and strategic bombers kept in a holding pattern as money originally earmarked for the B-1 is targeted for cruise missiles.

The Navy Trident submarine, replacement for the Polaris-Poseidon fleet now carrying nuclear missiles around the depth, gets additional money, but the purchase of Trident missiles has been reduced because of delays in building the first Trident submarine.

Under new starts in the strategic area, Carter has approved money for a spy plane, the TR-1, to succeed the U-2, and increased funding in a number of accounts related to space warfare.

The congressional complaint that the Pentagon is spending so much money on people that it cannot afford to buy as many weapons as it needs is likely to be repeated this year. About 51 per cent of the total Pentagon budget will be spent to pay, feed, train and house people.

President Carter's budget shows he will be hard-pressed to reduce arms sales abroad. In fact, they may well keep increasing despite his promises.

The Pentagon estimates that arms sales and grants will rise from $11.2 billion in fiscal 1977 to $13.2 billion in fiscal 1978, a $2 billion increase. Although estimates for fiscal 1979 are clouded by uncertainty about future policy decisions, the administration figures they will total about $13.4 billion.

Part of the upward surge is attributable to the administration's campaign to sell modern conventional war weapons to NATO allies. Carter has directed the military to focus their resources on Europe.

Under that set of Presidential priorities, the Army fared best in the division of the Pentagon money pie. Expressed in dollars of equal value, this is how much President Carter earmarked for each service in fiscal 1979 compared to what each got in the fiscal 1978 budget as approved by Congress:[TABLE OMITTED]

The $1.5 billion jump in the Army budget is attributable largely to buying new weaponry suitable for a war in Europe, with the start of production of the XM-1 tank and the purchase of new battlefield helicopters providing much of the upward pressure.

Brown said the Pentagon did not ask for additional money for building Navy aircraft carriers in the new budget and postponed sending a long-range shipbuilding program to Congress until March when studies will have been completed and assessed by Carter.

In advance of that study, Brown said he had decided to cancel the Navy's surface effects ship - a high speed vessel which skims over the waves on a bubble of air trapped under its hull - because its military role is not clear.

In the strategic area, the United States will continue to rely on its current nuclear deterrent force of 1,054 land intercontinental ballistic missiles; 636 missiles inside nuclear powered submarines, and 24 squadrons of B-52 bombers.

Brown said he had hoped to speed development of the MX blockbuster land missile, still on the drawing board, but has postponed such action until after determining whether basing the weapon in tunnels makes sense.

In contrast to the $1 billion the Air Force had originally planned to spend on developing the MX by this time, Brown is asking $158.2 million for the missile for fiscal 1979 compared to the $134.4 million appropriated for fiscal 1978.

The three questions hanging over MX. Brown said, are whether the public would support putting missiles in tunnels 10 miles long; whether the Soviets could destroy MX missiles even if they were kept moving back and forth inside the tunnels, and whether the weapon would be worth the money.

Critics of the MX contend it would intensify fears in the Kremlin that the United States was building a "first strike" missile force so it could disable Soviet missiles in a surprise attack. The MX would be accurate and powerful enough to destroy Soviet missiles now deployed.

"I would not rule out proceeding to full scale engineering development" later in the budget year if the questions about MX are answered in the missile's favor, Brown said.

The only significant initiative in the strategic area in Carter's budget is the development of the cruise missile which the President chose over the B-1 bomber.

The basic objective of the United States, Brown said, is to field enough forces to enable the nation to fight simultaneously one big war in Europe and a smaller one elsewhere-the 1 1/2-war strategy espoused by President Nixon.

During Brown's first tour of duty at the Pentagon from 1961 to 1965, the presidential guidance was to build enough forces to fight two big wars and one small one simultaneously - the 2 1/2-war strategy which the Vietnam War showed to be overambitious.

The reason the United States must increase its military budget, even though the nation is not at war, is to match the steady modernization and expansion of Soviet forces, Brown said. He said this was especially true of Soviet conventional forces threatening NATO - the reason the biggest increases in the new budget went for NATO-related accounts.