A paragraph was dropped from a story in yesterday's Post on the SALT II treaty. The paragraph said: A triumphal ending to the Iran crisis for President Carter could dramatically improve SALT's prospects in the Senate, according to both Senate and administration sources. One senator suggested that Iran could even "save SALT," provided it ends well for Carter.

Although there was no official comment from this capital tonight on Senate Majority leader Robert C. Byrd's announced postponement of the full Senate debate on SALT II -- a delay that may spell doom for the treaty -- the Kremlin has made very clear it considers the pact the bedrock upon which the rest of bilateral detente is based.

Soviet President Leonid Brezhnev warned President Carter during the Vienna summit last June that any attempt to revise the treaty would have "grave consequences" for superpower detente. And a week later, Foreign Minister Andrei Gromyko declared at a Moscow press conference that it would be "impossible" to renegotiate the treaty if the Senate rejected or altered it.

Gromyko asserted than that "the possibility of resuming negotiations is excluded" if the agreement is not ratified, and added that future relations would be clouded as well. "The situation will be very complex, very bad . . . Those bridges which lead from the treaty signed in Vienna to a possible SALT III would be destroyed," he declared.

However, hard-line pronouncements by Gromyko frequently form what might be called a first line of defense for the Kremlin on any issue. His pugnacious language draws headlines and anxieties in the West while the Soviets are examining the situation from their conservative, pragmatic perspective and readying a negotiating position.

A current example of this approach is the Soviet opposition to the NATO plan to base new nuclear-tipped Pershing II missiles in Western Europe. Gromyko last week said that if NATO members approve the plan, any possibility of new European disarmament talks would be destroyed. Yet Warsaw Pact foreign ministers in a communique toady from their East Berlin meeting left the door open for arms talks even if the West proceed with the new missiles.

The eventual Soviet reaction to Byrd's unpleasant prognosis is expected to blame the Americans entirely for the new development and to warn that only dire harm can result. How the Soviets will proceed is impossible to say, but there have been enough grim signs from Washington in recent weeks to forewarn Moscow.

The Kremlin is sure to have been at work formulating an approach to such an eventiuality. At present, the two nations have pledged themselves to abide by the terms of the expired SALT I agreement and one possible avenue could perhaps build a similar modus vivendi around the SALT II provisions even if the treaty is not ratified.

There is little reason to believe that the Soveits, with increasin economic problems at home, are eager to get into an all-out nuclear arms race with the United States.

Although Byrd blamed the Iranian crisis for the delay, there is no hint to be found in conversations with Soviet officials in recent days that suggests the slightest awareness here that the Kremlin's steadily hardening, anti-American propaganda line one the embassy seizure may badly damage long-term bilateral relations.

The Soviets seem to be counting on their U.S. Security Council support for the United States to defuse any hostile American reaction to the fact that Moscow has done little to help Washington extricate its 50 hostages from the grip of the revolutionary Moslem government now running the Soviet Union's southern neighbor.

Despite their reputation for hard-headed pragmatism in foreign policy matters during Brezhnev's tenure, the Soviets during the detente years also have proven adept at creating many of their own problems for themselves. The Kremlin's handling so far of the Iranian crisis seems to be the latest example of this. The consequences could reverberate long after the grim episode itself has ended.