An internal State Department memorandum partly blames the United States for the ''irritant'' in U.S.-Soviet relations caused by Moscow's nuclear treaty violations, terming it ''unrealistic'' to demand that Moscow dismantle the illegal Krasnoyarsk radar. One hard-line Reaganite privately described the memo as asking for a ''pre-emptive U.S. concession.''

Arguing that President Reagan should find new ways to end bickering over Soviet cheating, the proposal, stamped ''secret,'' would also shelve the seminal SALT II violation: Moscow's SS-25. That missile is a second ''new type'' ICBM, although SALT II permitted only one. But since the United States has nullified SALT II, the memo argues, the SS-25 has been ''overtaken by events'' and can now be ignored, even though it was one of the key violations that prompted Reagan to pull out of SALT II.

Although the memorandum from State's Policy Planning staff, dated May 22, has not been adopted by the department or, as yet, Secretary George Shultz, it says the United States must share the blame with Moscow for diplomatic problems arising from Soviet cheating. That has angered Reaganite Capitol Hill hard-liners, who say privately Reagan would never accept a proposal based on such reasoning.

In fact, however, if the plan wins support from Shultz and treaty-minded White House chief of staff Howard Baker, Reagan might well opt for what it calls ''compromise solutions'' to take Soviet cheating problems off the agenda. That would ease Senate ratification if Reagan and Soviet leader Mikhail Gorbachev sign an INF (intermediate-range nuclear force) treaty. Reagan and his wife, Nancy, want a nuclear treaty as a capstone for the Reagan era.

The most controversial part of the Policy Planning paper seeks to place part of the blame on the United States for unresolved treaty-violation issues that, it says, have become a ''recurring irritant in U.S.-Soviet relations.'' This ''compliance morass'' also hurts the United States in reaching new treaties governing superpower nuclear weapons, the memo states, moving on to what it considers the heart of the matter:

''Much of the blame for this unsatisfactory record belongs to the Soviets . . . but we can hardly claim to have made an active or persistent effort to solve problems. . . . {W}e have not been willing to advance compromise solutions of our own.''

Such Alice-in-Wonderland reasoning would seem out of place anywhere in the Reagan administration except the State Department. Even there, however, sources have told us that the highest officials engaged in U.S.-Soviet nuclear negotiations, together with working-level Sovietologists in the European Bureau, have strongly resisted the paper.

Soviet treaty violations do, in fact, have a surprisingly simple cure: Kremlin admission of error and agreement to correct old wrongs and commit no new ones. Compensatory action in Washington is not needed. Instead, officials at State who back the proposals from Policy Planning have decided that since the Russians cannot be negotiated into compliance, they want to launch an administration negotiation to find ''compromises'' that will buy Soviet compliance.

Some intelligence specialists here believe the Krasnoyarsk radar, when linked to other huge battle-management radars, helps to put the Soviet Union on the edge of what is termed a ''breakout'' position for completing a national anti-ballistic missile defense. That is precisely what the ABM treaty is supposed to protect the United States against. Shrouded hints from these specialists indicate new radars now being completed west of Moscow in overlapping circles are also moving the Soviet Union toward dangerous violations.

The frightening prospect of such Soviet activity is enhanced by intelligence reports of new Soviet surface-to-air missiles. SAM 5s, 10s and 12s now being deployed around Moscow are capable of defending offensive strategic missile silos farther from Moscow than the 150 kilometers permitted by the treaty.

If accurate, these reports lend weight to the views of critics who have read the Policy Planning memorandum and are unsettled by it. No matter how well-intentioned it is to get an INF treaty followed by Senate ratification debate not encumbered by past treaty violations, these critics insist the reality of past Soviet compliance must have precedence over finding seductive ways to feed the Russian bear.