Renewed U.S.-Soviet arms negotiations have given President Reagan's foreign policy an ambitious goal for his second term.

The agreement reached Jan. 8 by Secretary of State George P. Shultz and Soviet Foreign Minister Andrei A. Gromyko in Geneva to hold three-track talks on strategic- and medium-range missiles and space weapons improves Reagan's standing in Western European eyes and opens a new chapter in relations with Moscow.

But in the rest of the world, according to reports by Washington Post correspondents, the view of Reagan's second term brightens or dims according to various regional problems and points of contention.

From the Western European viewpoint, renewed U.S.-Soviet arms talks have removed or at least reduced one of the most likely sources of friction in the Atlantic alliance.

While generally supporting Reagan's first-term commitment to strengthening western defenses, Western Europeans were disturbed by what they saw as his lack of sophistication in world affairs and his administration's apparent inability to conduct serious negotiations with the Soviets.

Added to this was the specific concern of Britain and France, the two Western European countries with an independent nuclear deterrent, about the president's plans for constructing a defense system in space.

French and British leaders fear that their nuclear forces would lose credibility if the two superpowers pushed ahead with deployment of such antimissile systems. A related worry is that defense of the United States would no longer be coupled with that of Western Europe.

By agreeing at least to discuss space weapons with the Soviets, the administration effectively has defused the Europeans' immediate concern and made it less likely that the Kremlin will succeed in its presumed aim of driving a wedge between the allies on the subject.

Before the Geneva meetings, the Soviets seemed dubious about a "new" Reagan administration, but now both sides appear to have summoned the political will to move to the next stage in their relations. While not wholly persuaded of Reagan's credentials as a true believer in arms control, many Soviets clearly are relieved that, if nothing else, both sides are talking again.

Soviet analysts wonder about Reagan's part in this latest development. Shortly after the election, one analyst in Moscow wondered whether Reagan would seek a new role as peacemaker for his last term.

"If he has such ambitions to get in the history books in this way, that is one thing. Whether his advisers permit him, or whether he will use [his self-confidence] for foolish things, that is another," the analyst said. Latin America

In Central America, the administration is expected to continue and possibly intensify efforts to combat left-wing revolutionary forces, government officials and other political observers said, but they expect Congress to restrain him.

Nicaragua's Sandinista leaders repeatedly have charged that Reagan is preparing for direct military intervention in Nicaragua, but political observers in Managua, including U.S. and West European diplomats, said these charges seem aimed primarily at rallying domestic and international support.

The administration has said it will not accept consolidation of a Marxist-Leninist government in Nicaragua but has never made clear how far it would go if the Sandinistas do not respond to U.S. pressure to move toward democracy, curb their arms buildup and reduce links with the Soviet bloc.

"It hasn't been thought all the way through," a senior U.S. diplomat in the region said.

Administration policy is expected to become clearer in the spring after Congress decides whether to resume aid to Nicaraguan antigovernment guerrillas. The administration has pledged to push hard to restore the funding, cut off by Congress last May.

As part of a possible hardening of policy against Nicaragua, the administration reportedly was considering steps to reduce trade, increase the U.S. military presence around it and downgrade diplomatic relations. This course is said to be favored among top policy-makers.

Those favoring a more moderate line, backed by Shultz, have shown interest in a possible settlement through direct U.S.-Nicaraguan negotiations begun last June.

In El Salvador, officials expressed hope that continued U.S. support for President Jose Napoleon Duarte would enable the government to end the five-year civil war with left-wing guerrillas. They said continued U.S. military and economic aid is crucial, to give the government the upper hand in peace talks or wear down rebels in the field if negotiations fail.

"We can hope for reestablishment of peace in El Salvador with the help of our principal ally," a Salvadoran official said.

Regardless of the outcome of talks begun between the Salvadoran government and guerrillas in October, the administration is expected to maintain assistance to the government. Though Washington might look for new ways to aid the government -- by expanding U.S. intelligence-gathering activities, for example -- Reagan is not expected to increase U.S. involvement dramatically.

"It [direct U.S. military involvement] isn't necessary, and it would be a mistake because of the fallout here and in Congress," a U.S. military officer in San Salvador said.

A Duarte aide said both governments might concentrate more in Reagan's second term on helping the Salvadoran economy.

Most South American countries, as supporters or members of the Contadora group trying to negotiate peace in Central America, would like to see moderation of what they regard as inflexibly militaristic U.S. policies.

In general, though, South American leaders said they expect few changes in U.S. regional policies. They argue that continuing economic trouble in Latin nations, particularly on debt payments, may force Reagan to shift toward official intervention staunchly avoided for three years.

"The United States has to realize that, if it does not take steps to relieve the economic crisis, it will be faced with a group of hostile nations around Latin America within a few years," said Alan Garcia, leading candidate in Peru's April presidential election. The focus of U.S. relations with South American countries has changed dramatically since 1981 as a result of the region's political transition to democratic government.

When Reagan took office, six of South America's 10 major countries were under military rule. In the last three years, Bolivia, Argentina and Uruguay have returned to democratic government, and Brazil, the continent's major power, has moved toward installation of a civilian government this year.

The major exception is Chile, where Gen. Augusto Pinochet's government has staunchly resisted U.S. and internal pressure for liberalization. The Reagan administration has been forced in Chile to modify its "silent diplomacy" strategy of improving relations with military governments while discreetly seeking reforms.

During the next four years, some Chilean opposition leaders predicted, Santiago could become a major trouble spot in Latin America if the country continues its course toward violent internal conflict. The Reagan administration, they argue, has proved unable to respond effectively to the crisis, clinging to hopes of gradual movement by Pinochet toward democracy. The Middle East

Reagan remains an acknowledged friend and benefactor of Israel, and there are no major conflicts between the two countries at the moment.

The search for agreement in Lebanon appears the one area in Arab-Israeli affairs in which the United States has the smallest role. Israeli hopes for a negotiated troop-withdrawal agreement with the Lebanese have just about vanished, and U.S. influence in Damascus is limited and not likely to induce neighboring Syria to help break the stalemate.

Israel's first priority in its relationship with the United States is more aid and, though Israeli leaders may not obtain all of the almost $5 billion they are seeking over the next 18 months, they are going to try.

Reagan also will face new requests for increased aid and arms sales from moderate Arab states, particularly Egypt and Saudi Arabia. Egyptian President Hosni Mubarak and Saudi Arabia's King Fahd, both scheduled to visit Washington early in the new term, are likely to press Reagan to deal with Yasser Arafat and the Palestine Liberation Organization and to sell arms to Jordan, despite Israeli opposition.

A problem for Reagan will be how to deal with Arab allies' pressure for action on the Palestinian question, which they still regard as a major problem for their security. They worry that Reagan has relegated the Mideast and new Palestinian peace talks to the back burner and that they will be left in limbo, facing mounting violence and terrorism in the next four years.

Egypt and the United States face a looming crisis in the Sudan, where President Jaafar Nimeri, a staunch ally, is ailing. His death could lead to renewed civil war in southern Sudan and a possible power play by Libyan leader Muammar Qaddafi. Soviet-backed Ethiopia and Soviet-armed Libya are likely to work together in any such crisis against Egypt and the United States. Africa

Reagan's inauguration means a continuation of the "constructive engagement" policy that many Africans view as heavily tilted toward white-ruled South Africa. It also means Washington will cling to insistence that independence for South African-controlled Namibia, Africa's last colony, be linked to withdrawal of the estimated 25,000 Cuban troops in neighboring Angola.

Nonetheless, there are signs that conservative congressional Republicans and traditionally anti-South Africa liberals could make the next four years considerably less favorable to Pretoria.

Likely to pass Congress this year are economic sanctions -- whether a ban on sale of gold krugerrand coins in the United States, curtailment of bank loans or a mandatory code of conduct for U.S. companies doing business in South Africa. The administration has made clear opposition to these measures, but Reagan may face a difficult choice if sanctions pass with bipartisan support.

Elsewhere, African policy is expected to follow the same track, with such U.S. allies as Sudan, Somalia and Kenya receiving the bulk of military and economic aid. With aggressive promotion of free enterprise, the administration is riding a wave recently popular in much of Africa, where two decades of socialist rhetoric and economic centralization have largely failed.

Assistant Secretary of State for African Affairs Chester A. Crocker and others have made clear that the United States increasingly will direct aid toward countries seeking to increase incentives to private farmers and other budding capitalists. That could mean more money for such nations as Zaire, Zambia and Mozambique, all of which seek to inject new blood into lifeless, bureaucratically stifled economies.

One exception is Ethiopia, which, despite its Marxist government and pro-Soviet stance, is targeted to receive a record 215,000 tons of grain worth $110 million to help combat a severe food shortage. The food will serve to underline administration claims that it does not play politics with hunger.

Relations with Africa's newest nation, Zimbabwe, are likely to remain chilly, and some analysts predict that the U.S. aid commitment will continue to decline. Although many in Congress and the administration might like to write off Prime Minister Robert Mugabe and his Marxist-Leninist rhetoric, others argue that he presides over one of Africa's few economically viable states and that, after investing nearly $300 million over four years, the administration would be foolish to withdraw support. Asia and the Pacific

Trade questions are at center stage in relations with Japan, whose dominant business and political establishment welcomed Reagan's reelection and talks of further strengthening ties with the United States, easily its most important bilateral relationship.

The most serious problem for U.S.-Japanese relations is the trade imbalance. Talks between Reagan and Prime Minister Yasuhiro Nakasone this month produced general pledges to work together to solve it.

Japan wants to see U.S.-Soviet disarmament talks succeed. The Soviet Union is believed to have targeted large numbers of land-based and submarine-launched missiles on the country and its U.S. bases, and Japan would welcome a reduction of that threat.

U.S. diplomats in India speak enthusiastically about a "window of opportunity" for improved Indo-U.S. relations. But Prime Minister Rajiv Gandhi is at least publicly steering a middle course, promising to strengthen relations with the United States and the Soviet Union and expecting no major tilt in either direction.

Pakistan figures prominently in the equation, and Indian Foreign Ministry sources say efforts will not slacken to have the United States scale back armament of Pakistan, with which India has fought three wars in 37 years.

"Anybody who thinks that we will drop this issue to curry favor with the United States is sorely mistaken. Nothing has changed in that regard," a Foreign Ministry official said this month.

Pakistan's principal concern will be uninterrupted implementation of the five-year, $3.2 billion military and economic assistance package granted after it became a front-line state against Soviet expansion from Afghanistan. With Reagan's reelection, Pakistani officials have been sanguine about continued U.S. backing, which also has included more than $350 million in cash, food and relief supplies to nearly 3 million Afghan refugees in Pakistan. That does not include funds reportedly earmarked for covert military aid to Afghan insurgents fighting Soviet occupiers.

U.S.-Filipino relations will depend on the outcome of local elections this year and a scheduled 1987 presidential election. Regardless of whether President Ferdinand Marcos remains in power, the United States will face problems because of the presence there of two U.S. military bases. The accord governing U.S. use of the bases expires in 1991, and alternatives may be needed if a government that wants to remove them takes power.

Sentiment against the bases appears to be growing with increasing public acceptance of the radical Communist Party of the Philippines and its armed wing, the New People's Army. A group of moderate opposition presidential contenders has endorsed a platform calling for removal of the bases, and a conservative contender who refused to go along, former senator Salvador Laurel, has proposed a national referendum on the issue.

In New Zealand, the United States must deal with a Labor government ban on visits by nuclear-armed and powered ships, according to a senior State Department official. The only such ban by a U.S. ally, it has implications for other U.S. alliances.

Because the United States refuses for security reasons to specify whether any ship or plane is nuclear-armed, the ban means no port calls by U.S. Navy ships. U.S. officials think that incompatible with the ANZUS alliance.

In addition, a small but growing antinuclear movement in Australia wants to follow New Zealand's ban example and remove three vital U.S. communications bases.