fter considering military manpower and equipment cutbacks that had alarmed the United States and other NATO nations, Denmark has decided instead to increase its defense spending by 2 percent above inflation in the next three years.

Danish officials said they hoped this move would be seen in Washington and other NATO capitals as "an important signal that we are not opposed to a strong defense." Denmark, one of the world's most affluent countries, has been singled out by U.S. critics as a prime example of a trend toward pacifism in Western Europe, and has been accused by the United States and other allies of being unwilling to pay its share of NATO costs.

Forced by a continuing economic crisis to lower Denmark's standard of living and curb its generous social welfare programs, Prime Minister Anker Jorgensen's left-of-center Social Democratic government allowed defense spending to rise only enough to match inflation for 1980 and 1981. Jorgensen had proposed continuing this policy, which would have forced the Danish military to remove all troops from the Sjaelland islands, where Copenhagen is, phase out a number of coastal patrol boats and postpone improvements to air defenses.

NATO officials made clear their concern that this would make Denmark more vulnerable to being overrun by enemy forces before NATO reinforcements could arrive, potentially endangering both allies such as nearby Norway and the neutrality of neighboring Sweden. Denmark's islands and the Jutland Peninsula bordering West Germany are crucial to the control of the strategic strait between the Atlantic Ocean and the Baltic Sea, where much of the fleets and many of the ports of the Soviet Union and its Warsaw Pact allies are.

But after many months of negotiations with opposition parties in parliament, Jorgensen's minority government made these cutbacks unnecessary by agreeing late this summer to increase military spending by 1 percent in 1982 and .5 percent in 1983 and 1984. These increases will come on top of the defense budget's built-in indexing for inflation, higher fuel costs and fluctuations in exchange rates.

Jorgensen won approval of this three-year defense agreement from his own Social Democratic Party last week, despite vocal objections from left-wingers, including some Cabinet members, who argued against increasing military spending while scaling down social welfare programs. Danish sources suggested that Jorgensen originally proposed no increase in defense expenditures in order to mollify this politically threatening minority in his party, knowing that an acceptable military spending increase would still result from negotiations with the four opposition parties to the right of the Social Democrats.

"I'm very satisfied with this agreement, especially if you look at our economic situation," Jorgensen said in an interview.

Denmark's increase in defense spending will still be well below the NATO target of 3 percent a year above inflation. But Jorgensen and other Danish officials pointed out that some allies who originally promised to meet or come near this goal are now unlikely to do more than keep up with inflation. They were referring to West Germany, among others. Only the United States and Norway are expected to meet or surpass the 3 percent target, and even the Reagan administration has said it must scale down its defense spending.

By contrast, one Danish source said, "We will now be spending somewhat more than expected. We hope this will send some kind of signal to the rest of the allies that we are striving to support the alliance line within our own economic and political difficulties."

Denmark got into trouble with the rest of NATO, Jorgensen said, because "we said very early that we might have a problem reaching 3 percent. Now, most of the other countries have exactly the same situation as we do. But it's only lately come to the surface."

With the Soviet threat looming larger and recession forcing choices between military and social welfare spending, the European press coined the term "Denmarkization" to describe what happens to an ally that enjoys NATO's protection but does not like paying for it. Opinion polls in Denmark showed a record 70 percent support for NATO membership but less than 50 percent approval of increased defense spending.

"There is strong support for NATO in Denmark and strong support for a credible defense budget," insisted Jorgensen. "But let me underline that, in my opinion, we have to be very careful because a demand from the U.S. or others for still higher defense budgets could cause difficulties here."

Jorgensen said many Danes did not think they should be participants in an unending arms race between the superpowers.

Danish sources also expect another tough political test for Jorgensen late this year or in 1982, when he must decide about storing tanks and other heavy equipment in Denmark for U.S. troops to be rushed here if Denmark is attacked. Leaders of Denmark's growing peace movement--still a minority, but a political force because of its impact on the news media--argue that this could violate Danish policy against stationing nuclear weapons or foreign troops on its soil in peacetime. But only the equipment would be kept here in peacetime, and it would not include nuclear weapons.

Jorgensen has already given Denmark's approval to a new NATO proposal that would earmark reinforcements for specific European countries rather than larger regions. Once NATO's European command decides which U.S. troops to designate for Denmark, negotiations would begin between Denmark and the United States on prestocking equipment for them.

Despite strong dissent from its own peace movement and the left wing of the ruling left-of-center Labor Party, Norway last year negotiated an agreement with the United States to store heavy equipment, including weapons, for a U.S. Marine brigade to be airlifted there if war starts. Both Norway and Denmark also have similar arrangements with other European allies.

With relatively little controversy, Denmark has already started stockpiling ammunition at strategically important military airfields in Jutland for 120 U.S. Air Force fighter planes that would use those bases in wartime. Denmark also has joined Norway, Belgium and the Netherlands in coproduction of U.S.-designed F16 fighters. This is the biggest arms deal in Denmark's history and has placed a heavy burden on its defense budget.

Denmark's self-defense capability and its contribution to the protection of NATO's northern flank "has developed in the last few years in a much better way than people have said," Jorgensen argued. "There has been a relatively good modernization of our defenses."