A long-range plan to speed the flow of U.S. air and ground reinforcements to Europe in the event of war or an approaching crisis was agreed upon here yesterday by the defense ministers of the North Atlantic alliance.

U.S. officials, who revealed the plan, described it as "revolutionary" in comparison to what could be done now in a crisis.

The plan amounts to stockpiling vast amounts of additional Army equipment in Europe and then flying five full army divisions plus support - the equivalent of roughly 100,000 to 150,000 men - from the United States to scores of European airfields to join roughly five U.S. divisions already here.

In addition, roughly 60 squadrons of tactical warplanes would be flown over to join roughly two dozen such squadrons currently based here.

U.S. officials say the plan to triple the air strength within one week in a future crisis could be ready reasonably soon. Getting the capability to double U.S. troop strength here within two weeks, however, will take about four to five years to put into effect. It will also be dependent upon congressional approval and "highly dependent," the officials said, upon cooperarion of European allies who are supposed to provide reception facilities and equipment to move the troops into battle positions.

The officials said the plan basically means getting away from using the sea lanes to ship troops and instead using all available air transports - military and commercial - to fly the troops overseas.

The oficials claimed that under the plan, the first division of army reinforcements could be in Europe within two days and three divisions within one week. Now it would take an estimated six weeks to move three divisions.

The United States has long stockpiled equipment - extra tanks, trucks, supplies and ammunition - for an extra 2 1/3 divisions in Europe. This stockpile would now be increased to supply five divisions.

The U.S. and NATO effort to focus attention on building up conventional forces in Europe is meant in part to counter a continuing modernization of Warwaw Pact forces which already have a numerical advantage in troops, tanks, artillery and medium-range missiles.

It is also designed, however, to shift attention to the conventional field in anticipation of a new U.S. Soviet arms agreement this summer on strategic nuclear arms. If the two superpowers are perceived as roughly equal in ocean-spanning missiles and bombers, then the White House also wants NATO to be viewed as able to withstand a conventional attack.

The build-up plan is part of what NATO calls its "long-term defense program."

This is on effort set in motion by President Carter at the NATO summit meeting a year ago in London and meant to help the 13 countries of the allance develop better coordinated plans into the 1990s for costly defense projects.

There are 10 high-priority projects in the plan U.S. officials said. They added that NATO had also ogreed yesterday on what was called "a completely unprecedented alliance program" in the field of electronic warfare. This is the attempt to knock out opposing weaponry through electronic jamming or deception.

In another area, these officials claimed that about nine European countries had agreed to "consider" an expansion of their combat reserves in which experienced reservists, now used only to fill individual places, would be reorganized into new combat brigades.

The two-day meeting of NATO defense ministers that opened yesterday is meant to put the stamp of approval on the long-term plan so that it can be presented to the heads of government at the NATO summit meeting in Washington May 30 and 31.

The long-term plan is being counted on, by the Europeans and especially by the Carter administration, to put a positive face on the summit and to pump new life into an alliance that will be 30 years old next year. The effort to put a positive face on things may also explain the rather dramatic language used by U.S. oficials to describe yesterday's actions. The officials briefed reporters under rules that say they may not be identified.

Nevertheless, other events continue to cast a shadow over NATO unity.

It now seems clear that a hoped-for declaration to the summitt on renewed faith in the alliance will probably not be signed by Turkey, which is embittered by a congressionally imposed arms embargo stemming from the invasion of Cyprus in 1974.

Meeting sources said that NATO Secretary General Joseph Luns raised the embargo issue in closed session, expressing the hope that the president and Defense Secreatary Harold Brown could convince Congress to change its mind. Brown reportedly said that the administration would do all it could.

Events in Africa also hung over the opening day session!

NATO's annual intelligence report on Sovier-led Warsaw Pact forces called attention to the Kremlin "increasingly demonstrated willingness to exploit situatioms of instobility, particularly in Africa . . . using Cuba as a proxy."