The day after George P. Shultz was named to succeed Alexander M. Haig Jr. as secretary of state in June 1982, an internal State Department briefing paper on Central America outlined the existing Reagan administration vision of "Where We Go From Here" for the new chief U.S. diplomat:

"Assuming that Cuba and Nicaragua do not substantially increase the stakes in Central America, the secret to success will be a steady and sustained effort. Barring serious miscalculation by the other side, there will be no opportunities for quick decisive action to end the problem."

Just about a year later another internal paper, prepared for a memorable July 8 meeting of President Reagan and his National Security Council, portrayed the situation in far harsher terms:

"The situation in Central America is nearing a critical point . . . . It is still possible to accomplish U.S. objectives without the direct use of U.S. troops (although the credible threat of such use is needed to deter overt Soviet/Cuban intervention), provided that the U.S. takes timely and effective action."

This notable shift in the administration's sense of urgency underlies a major change in the scale and intensity of U.S. actions, which have heightened controversy in Washington in recent weeks and brought the situation in the region to the threshold of new confrontations.

The shift also has raised questions about whether the administration is departing from a "long-haul" strategy in the region for short-term bets that promise earlier gains but risk more serious crises, just as the United States heads into a presidential election year.

Senior administration officials, in a series of interviews last week, described recent U.S. military, paramilitary and diplomatic moves in Central America as reactions to the activities of others rather than independent initiatives. The officials also said that, in most cases, the administration is proceeding along established paths rather than veering off in new directions.

In the White House, Pentagon and State Department, however, there was agreement that the developments of the past month have raised the intensity of U.S. efforts.

"The intensification of efforts all across the board, in all areas--this is the key change," one official said. Another said: "There is a certain increase in intensity, but not completely out of the previous ballpark. There is an evolution but not a strong change in direction."

However one describes the shift, there is little doubt that recent decisions and events have produced a new sense of maneuver and conflict in both Washington and Central America.

The central point of disagreement within the executive branch, according to official sources, is the management of consent at home: how far and how fast the administration can go in Central America without exceeding the tolerance of the public and the political system in the United States.

Since the July 8 National Security Council meeting, a session deemed so important by Shultz that he traveled 24 hours straight to get back in time from the Middle East, there have been these developments:

* Reagan on July 12 ordered U.S. military exercises in Central America of unprecedented duration for that area, about six months, and very large size, involving 3,000 to 5,000 U.S. ground troops in Honduras and a succession of naval task forces offshore.

According to administration officials, the Pentagon planning process began in May and the maneuvers were discussed in at least six inter-agency meetings since mid-June, primarily as a response to the increased shipment of Soviet and eastern European military supplies to Nicaragua and reports of additional Cuban military advisers arriving in that country.

These activities were not fundamentally different from those previously reported by U.S. intelligence, but to administration officials they represented an increase in communist involvement that needed to be countered.

When the maneuver order became public in a press leak July 19, the unprepared administration vacillated between statements suggesting that the exercises were routine and day-by-day revelations of the size, scope, planned activity and intimidating character of the operation. Briefings for Congress were tardy and vague.

It was a "major mistake" not to move quickly after the initial disclosure, a senior administration official said last week, adding that failure to do so "created ill will and created the impression of bungling by the administration."

* The CIA by mid-July had drawn up plans for a major new expansion of the U.S.-backed "secret army" of anti-government guerrillas in Nicaragua, which already had been growing at a rate that alarmed the House Select Committee on Intelligence and many others on Capitol Hill.

The new plan for 12,000 to 15,000 anti-Sandinista fighters, which is reported to have been approved in general terms as part of Reagan's July policy-making, would double the numbers of U.S.-funded guerrillas reported by the CIA to Congress as recently as early May.

Some CIA officials are reported to have opposed the latest plan for expansion of the anti-Sandinista force known as the "contras." The U.S.-backed insurgents have not been doing well militarily, according to sources in the region, falling behind their timetable for rapid military gains against Managua's forces and beginning to speak openly of needing direct U.S. intervention to win their fight.

A report from Honduras suggested that the U.S. military maneuvers are designed in part as a shield to protect Honduras and seal off Nicaragua while the contras make a major military push inside Nicaragua later this year. Under questioning on this point, Shultz told the Senate Foreign Relations Committee last Thursday that the manuevers include no "plan" for an "operational program" or any intention to engage anyone militarily.

* The Pentagon drew up plans to increase the number of U.S. military advisers in El Salvador from 55 to 125, bringing a reaction from prominent Republicans as well as Democratic members of Congress. No decisions were made, although Shultz confirmed that a major increase is under discussion within the administration.

* Reagan on July 18 named former secretary of state Henry A. Kissinger as chairman of a bipartisan commission charged with producing a long-range plan for Central America.

The commission was intended to win and consolidate support for U.S. policy, but the naming of the high-flying celebrity as chairman set off a round of attacks by Kissinger's enemies on both the left and the right, plunging the policy on Central America as well as the administration itself into even greater controversy.

* The "Contadora group" of concerned Latin American governments held a foreign-ministers meeting July 15 and a heads-of-state meeting July 17, and sponsored a meeting of the five key Central American foreign ministers, including El Salvador, Honduras and Nicaragua, July 28 to 30. No concrete results were reported.

U.S. special envoy Richard B. Stone, meanwhile, met July 31 for the first time with a representative of the political arm of the Salvadoran guerrilla movement, Ruben Zamora, and subsequently flew to Managua for talks with the Nicaraguan government.

According to a senior State Department official, Stone's objective is to set up "no-agenda" talks between the Salvadoran government and Salvadoran rebels, which the United States hopes will concentrate on possible rebel participation in the planned elections in that country. Stone is "not discussing the substance" but is talking about the time, place and mechanics of government-rebel talks, the official said.

* In a widely noted public statement, Nicaraguan junta coordinator Daniel Ortega announced July 19 that his government is willing to discuss the cross-border flow of arms and other pressing issues in multinational discussions with its neighbors, despite its continuing conviction that bilateral talks are best.

This was interpreted as an important concession, although the initial multinational discussions between Nicaragua and the other Central American foreign ministers did not produce results.

* Cuban President Fidel Castro announced July 29 in U.S. television interviews that he is willing to halt military aid to Nicaragua if an agreement is reached for all countries to stop sending arms and advisers to Central America.

Well-informed sources said this is a more specific rendition of a basic position that Castro and his government have taken in private messages to the United States and occasional public statements for nearly two years, since Castro apparently became convinced that the leftist guerrillas would be unable to triumph in additional Central American countries in the short run, if the United States continued to give strong backing to the governments they were fighting.

* At home, political opposition to administration policy in Central America broadened and deepened as a result of the developments and a sense of gathering crisis.

The House on July 28 voted 228 to 195 to cut off undercover CIA aid to the anti-Sandinista guerrillas, despite strong administration and Republican appeals against the measure. That action had no immediate practical effect in the absence of a parallel Senate vote, but it placed one body of Congress and, to an extent, the Democratic Party on record against the "secret war."

This could have serious consequences if the House persists in denying funds for the CIA program in authorization and appropriations measures for fiscal 1984, or if the United States should be drawn into war by support of covert action that the House has disapproved.

Democratic political figures in and out of Congress increased their criticism of administration policy following the House vote. Last Wednesday, Sen. Edward M. Kennedy (D-Mass.) charged that the administration without proper consultation with Congress "has put our country on a track toward war in Central America." Joining him in offering a bill to ban the U.S. military maneuvers without congressional approval was Sen. Gary Hart (D-Colo.), a candidate for his party's presidential nomination.

Public opinion polls, meanwhile, continued to report that the American people still disapprove of administration policy in Central America by wide margins and fear that the policy is moving toward U.S. involvement in another war.

Surveying the onrushing developments late last week, a senior State Department official with major responsibility in this area remarked, "There is a feeling of crisis, but I don't look at it as crisis time." He added, "The whole process in Central America is intensifying. There have just been an extraordinary amount of things happening in a short period of time."

Asked what they see ahead, various officials sketched out expectable points of tension and conflict this fall and winter, but with an unusual degree of uncertainty about the outcome.

In El Salvador, there is no sense of an early turning point militarily or economically. The pivotal country of conflict in the region seems unlikely, as it has been for some time, to move decisively. Politically, the expected presidential elections have been put off for the time being for technical reasons, and possibly because of increasing concern that presidential balloting could polarize that country in damaging fashion between far right and centrist movements that now coexist under a shaky governmental umbrella.

In Nicaragua, the struggle between the contras and the Sandinista regime seems likely to grow apace and perhaps to take a decisive turn within the next six months. The direction of that turn is likely be affected by decisions in Moscow, Havana and Washington, including those on Capitol Hill, as well as by combatants in the battle zone, and it is considered highly unpredictable. At present, an administration official said, the contras are placing pressure on the Sandinistas, "although not very strong pressure."

In the negotiating arena between the Salvadoran government and rebels and between Nicaragua and its neighbors, contacts have now been made, preliminary concessions on procedures granted and some of the ground rules for discussion are in the process of being drawn up. But negotiation of substantive issues has yet to begin in earnest, and there is no optimism about early results.

In Washington, the administration is likely to go back to Congress for more money this fall for military and security assistance to several Central American countries, especially El Salvador. U.S. officials pointed out that this spring and summer they were able to obtain only about half of the funds they sought to pursue the war, and they said this shortfall will have to be made up if the military plan in El Salvador is to be fulfilled.

As it has from the start of the Reagan administration, the need for additional funds will provide critics in Congress and elsewhere with levers to affect the policy. How to deal with this political problem at home amid deepening conflict in the region continues to be the subject of an internal debate that is deeply affected on all sides by the painful memory of failure in Vietnam.

The State Department, which deals intimately with Congress but often as a supplicant, fears that dramatic or abrupt moves beyond the congressional consensus may bring politically damaging rebellions and even disastrous restrictions from the lawmakers. State therefore favors long-term, low-key, gradual strategies with a minimum of surprises.

The Defense Department, reacting against the incremental escalation of the Vietnam period, is inclined to insist this time on large-scale resources and the leeway to use them from the start. Along with the Reagan White House, which has been calling the tune since early this year, the Pentagon seems ready to test the political limits now rather than accept restrictions that could inhibit its efforts later.