A tentative agreement on missile defense capabilities between the United States and Russia and other former Soviet republics broke a logjam in the Senate Friday, ap-par-ent-ly clearing the way for final passage of the 1997 defense bud-get.

The preliminary agreement, outlined in a letter to lawmakers from the National Security Council, sets limits on the capabilities of so-called theater missile defense systems that are acceptable to Re-pub-lican lawmakers.A copy of the letter was obtained Friday by The Associated Press.

With word of the agreement - part of negotiations under way in Geneva - senators were able to clear away the final disputes on the $265.5 billion defense bill and scheduled a vote for July 10.

A key issue in the Anti-Ballistic Missile Treaty negotiations in Geneva was the dividing line, or "demarcation," between theater and national missile defenses.

Republicans long have opposed placing an artificially low capability limit over theater missile defenses such as the Patriot missile system. That could leave U.S. troops in the field more vulnerable to missile attack.

The importance of the demarcation is to prevent either superpower from developing "theater" missile defenses that could be used to defend an entire nation, thus getting around the limits in the treaty.

Without the agreement "we simply would not been able to have achieved what we just announced." said Sen. John Warner, R-Va., a senior member of the Senate Armed Services Committee,

William Danvers, special national security assistant to President Clinton, wrote the lawmakers that on June 24, negotiators from the United States, Russia, Ukraine, Belarus and Kazakhstan reached preliminary agreement on limiting the capabilities of theater defenses at "precisely the . . . demarcation standard the Congress directed us to obtain."

In addition, the negotiators reached an understanding on how the former Soviet republics may join in the 1972 ABM Treaty.

A senior White House official, who spoke Friday on condition of anonymity, said the Clinton administration is now reviewing the preliminary agreements reached in Geneva and is "pleased" with the results.

Republicans originally wanted to require Senate approval if former Soviet republics other than Russia were to join in the ABM treaty. This provision had prompted a veto threat from the administration.