The past week has been made unusually interesting by what appears to be an abrupt reversal in the attitude of the Reagan administration toward the Soviet Union.
The change was framed in a formal presidential speech in the East Room at the White House before a selected audience. It was broadcast over radio and television to both a national and worldwide audience. It was made a ''big thing.''
In the speech, President Reagan declared that his policy toward the Soviets is one of, ''Credible deterrence, peaceful competition, and constructive cooperation.''
The Reagan words were followed one day later by a speech by his secretary of state, George Shultz, at the opening session in Stockholm of the East-West conference on security in Europe. Mr. Shultz repeated the Reagan theme. He said, ''We are ready for negotiation.'' He said the United States wants ''a more stable, consistent, and constructive East-West relationship.''
The President proposed that, as a means to ''constructive cooperation,'' the US and the USSR ''make a major effort to see if we can make progress in three broad problem areas.'' He identified the three areas as being ''to reduce the risk of US-Soviet confrontation,'' ''to reduce the vast stockpiles of armaments in the world,'' and to seek ''a better working relationship.'' That same working relationship was apparently strengthened by the five-hour meeting in Stockholm between Mr. Shultz and Soviet Foreign Minister Andrei Gromyko.
In other words, the week was marked by a carefully orchestrated and heavily underlined switch in declaratory US policy at the beginning of the presidential election year and 13 days before Mr. Reagan has promised to announce his intention to run or not to run again for office. Thus, if he runs, he will run waving an olive branch.
This is sad news for Mr. Reagan's rivals from the opposition Democratic Party. They had been geared to attack him as a man of war. They expected to find him most vulnerable on that issue. At a mass debate of all eight current Democratic candidates on the day before the Reagan speech, the stress was on the alleged war dangers that Mr. Reagan, according to the Democrats, had unleased by his weapons-building and his use of such weapons in his foreign policy.
But what does it mean to the outside world in general and to the Soviets in particular?
Mr. Shultz cast light on one corner of the areas of strain in US-Soviet relations. He declared that the US ''does not recognize the legitimacy of the artificially imposed division of Europe.'' But in a briefing with reporters he denied that he was questioning the sovereignty or boundaries of the countries of Eastern Europe.
So, Washington does not like the Iron Curtain but is not going to do anything positive to bring it down. And that leads to the old question, ''So what's new?''
There is often a gap between declaratory and operating policy. The new Washington posture, with olive branch raised high, is the reverse of the old posture with Mr. Reagan accusing the Soviets of being the world's ''focus of evil.'' This is an invitation to talk. The old posture was one of defiance and hostility.
But the old Reagan administration policy toward the Soviets was not so hard in practice as it was in precept. Mr. Reagan early on canceled the grain embargo his predecessor, Jimmy Carter, had imposed on the Soviets. And Reagan's lieutenants sought, and got, a Soviet commitment to buy even more US grain.
In other matters more important to the Soviets, the Reagan administration has been cautious. Weapons have found their way to the Afghan resistance, but the US has not allowed itself to be seen in the actual delivery.
The Reagan administration gave rhetorical sympathy to the Solidarity movement in Poland, but no weapons, and no encouragement to civil war.
Reagan denounced the Soviet shooting down of the Korean airliner, but he did not impose sanctions.
Reagan in his speech this week mentioned the Middle East and ''the sophisticated weapons'' the Soviets have introduced there as being something that ought not to have been done. But US planes and warships off the coast of Lebanon have refrained from shooting inside Syria, where the new Soviet weapons and Soviet gunners are located.
The hardest thing the Reagan administration has tried to do to the Soviets was the 1983 effort to block completion of the natural gas pipeline from Siberia to Western Europe. But that one really ''hard'' project was vetoed by the NATO allies in Western Europe.
John Foster Dulles used to preach ''roll back'' of the Iron Curtain. But he practiced careful ''containment.''
Until this past week, President Reagan sounded like a second generation ''cold warrior.'' But his actual policy toward the Soviets has been much like the cautious ''containment'' Mr. Dulles practiced.
Hence, today's ''new policy'' just might lead to a fresh dialogue between Moscow and Washington. But startling new developments of real substance, leading to a revival of ''detente,'' are not to be expected tomorrow, next week, or next month.