New Delhi — It has often been said that the major planks of Indian foreign policy were Indira Gandhi's ideas. They are:
* Strong commitment to a nonaligned posture for the third world.
* Close ties with the Soviet Union, cool relations with the United States.
* Suspicion toward Pakistan.
* Desire for unchallenged supremacy in south Asia.
In fact, they were not just Mrs. Gandhi's policies. Rather, they reflect a longstanding consensus in India on what its strategic interests are and on what route the country should take. Thus, although there is certainly room for maneuver, neither Indian nor foreign diplomats expect any dramatic or immediate change under Prime Minister Rajiv Gandhi.
As Mr. Gandhi settles into his unenviable task, taking over after his mother's assassination, two major questions mark Indian foreign policy: What will happen between Pakistan and India? What will be the American attitude toward Mr. Gandhi's government?
Annoyed by what was long perceived in Washington as Mrs. Gandhi's flirtation with the Soviet Union - on which India is largely dependent for arms - India's foreign-policy makers have for some time believed, as did Mrs. Gandhi, that Washington never took this vast democracy terribly seriously.
During his meeting last weekend with US Secretary of State George Shultz, Mr. Gandhi voiced not unexpected concern about United States arms supplies to Pakistan and about Pakistan's nuclear program - long a source of friction between New Delhi and Washington.
New Delhi needs reassurance, and European diplomats have expressed hope that the Reagan administration will move quickly in an effort to dispel some of the suspicion that has grown over the years. The Soviet Union has already shown itself most anxious to woo India's youngest prime minister.
In 1983, three years into his grooming as his mother's dynastic heir, Mr. Gandhi was invited to the USSR. Though he was only a junior member of parliament and one of five general-secretaries of the ruling Congress (I) Party, he was treated as a most senior minister or a visiting head of state. This, in spite of the presence in Moscow of West German Chancellor Helmut Kohl at the time.
In his first major exposure to the art of international statecraft, Gandhi met with the powerful defense minister, Dmitri Ustinov, first Vice-President Vasily Kuznetsov, and Foreign Minister Andrei Gromyko.
The Soviets sent a high-powered delegation to Mrs. Gandhi's funeral, headed by Prime Minister Nikolai Tikhonov. During a 40-minute meeting between Mr. Tikhonov and Mr. Shultz, there were reportedly many heated moments. Shultz could barely disguise his fury over allegations in the Soviet press that the Central Intelligence Agency was behind Mrs. Gandhi's death.
According to Shultz aides, Tikhonov attempted to distance the Kremlin leadership from the remarks. Nonetheless, the allegations have continued throughout the week. But other than India's pro-Moscow newspaper Patriot, the English-language press in India has given the allegations scant attention.
Pakistan's leader, Gen. Muhammad Zia ul-Haq, has made a good start in improving relations. Knowing how quickly India often tends to attribute its internal problems to a ''foreign hand,'' he sent two messages to Mr. Gandhi the day he was sworn in, pledging his commitment to bettering relations between the two long-time enemies. He followed up the messages with a personal phone call, then came to the funeral of that feisty, determined lady whom he basically did not like.
Since the partition of the subcontinent in 1947, it was the first time a Pakistani chief of state had attended a state funeral in India. The leader of largely-Muslim Pakistan did so at some personal risk, as thousands of Hindus shouted anti-Pakistan and anti-Sikh slogans in their violent rampage against Sikhs. (Mrs. Gandhi was killed by two Sikhs.)
Shortly before Mrs. Gandhi's death, friction between India and Pakistan had reached its highest level in years. She had canceled ongoing talks between the two countries, set for July, to discuss the outlines for a friendship treaty or nonaggression pact. She blamed Pakistan for aiding Sikh militants in Punjab State - charges that Pakistan adamantly denied. Clashes between the two nations, which have gone to war three times, had increased in recent months along the Kashmir border. There has been growing international concern about a conventional arms race escalating between the two nations and about their nuclear weapons capabilities.
At a gathering Sunday with foreign journalists, Zia again denied Pakistani complicity in the Punjab's troubles - including Indian allegations that Pakistan was training Sikh extremists and providing them arms. ''I invite India to find the truth,'' he said. ''If the opportunity presents itself, I will certainly invite the new Indian premier to send a team of investigators to Pakistan to look around, to ask questions, whatever they want to do.''
It was not possible to verify whether Zia actually broached this with Rajiv Gandhi later in the day when the two met privately for 15 minutes. Nor was it possible to find out whether the Pakistani leader took any major initiatives for reviving the moribund bilateral talks.
But before meeting with Mr. Gandhi, Zia did tell the foreign reporters that the assumption of power of a young man - who represents the post-partition generation not saddled by the ''inhibitions and animosities'' of those years - was decidedly a positive sign.
''Therefore it is natural to expect a fresh dynamic, approach (from him) to a chronic problem,'' Zia said.
According to a Western diplomatic official, the greatest missed opportunity of Mrs. Gandhi's nearly 16 years in office was not offering an olive branch to Pakistan after their bitter 1971 war.
Instead, the daughter of the late Prime Minister Jawaharlal Nehru, who had lived through the searing years of partition at her father's side, continued to act toward Pakistan in a highly suspicious, negative way.
Mr. Gandhi now has the opportunity to return Zia's gesture and perhaps finally heal the wounds between the subcontinent's ''terrible twins.''