The Pentagon's newest five-year plan for rearming American would cost just under $2 trillion if Defense Secretary Caspar W. Weinberger gets his way, according to an internal guidance document obtained yesterday.

Weinberger, in setting forth budget targets for the military services for fiscal 1985 through 1989, would keep them on a steadily rising plane, reaching $464.7 billion in fiscal 1989 compared with the $274.1 billion requested for fiscal 1984, the budget now before Congress. The totals for fiscal 1985 through 1988 are the same as projected earlier this year.

This year's 109-page guidance paper, first published by the privately owned Defense Week publication, is markedly softer in tone than the one issued to the military services last year for fiscal 1984-88. The new paper, much of it unclassified, steers clear of using the term "protracted" nuclear warfare, for example.

Weinberger said last year that the armed services must be prepared to fight a "protracted" nuclear war. His mention of the need for such preparations kicked up a storm of controversy, even though he repeatedly said he was not breaking any new ground in nuclear policy.

This year's guidance emphasizes the need to tailor forces for African and Persian Gulf contingencies, including finding ways to contain such leaders as Libya's Muammar Qaddafi.

The United States must "develop plans to counter militarily Soviet, Cuban and Libyan forces operating from Libyan bases which pose a threat to U.S. or NATO forces," Weinberger stated.

"U.S. interests in Africa will grow in the decade ahead," he said in opening the section of his guidance on that continent. "Critical commercial and military LOCs lines of communication traverse or run in close proximity to this resource-rich continent."

"Therefore," he continued, "we must counter Libyan subversive actions throughout Africa by assisting friendly states militarily, where appropriate, and by weakening Libya's ability to interfere."

Also, the guidance said, "we must maintain and, as required, expand access and transit rights in pro-western African states for the deployment of U.S. forces to Africa, the South Atlantic and contiguous areas; and work to deny or reverse similar access and transit rights to the Soviets."

In discussing the Persian Gulf, Weinberger directed the Air Force by 1986 to store in the area the equipment needed to "support planned deployments." The Army should stockpile 50,000 pieces of equipment in the region as well, Weinberger said.

"U.S. forces will be rapidly projected into the region to directly confront the Soviet attack and assist regional and western allies, where available, in the defense of the oil fields and the Arabian peninsula," he said.

Underscoring the fact that the same Rapid Deployment Force troops that would respond in the Persian Gulf also have been designated to fight in Europe if war breaks out there, Weinberger said NATO troops should be ready to fill "defense gaps due to possible deployment of U.S. reinforcements to Southwest Asia rather than Europe."