The United States Friday expressed disappointment after Russia effectively vetoed a plan to keep peace monitors in Georgia after June. U.S. officials say Russia insisted on a plan that would implicitly recognize the self-declared independence of the breakaway region of South Ossetia.

The State Department said it regrets the breakdown of talks over extending the presence of the peace monitors in Georgia and is disappointed by the Russian position. But State Department officials say they still retain hope that Moscow will accept a Greek compromise plan and allow the continuation of the peacekeeping effort by the Organization for Security and Cooperation in Europe.

Negotiations in Vienna that had been underway for several months were suspended Thursday, with the Greek chairman of the talks saying that a consensus could not be reached.

A Greek proposal would have let OSCE monitors operate freely throughout Georgia including in pro-Russian South Ossetia, which Russia recognized as independent after last year's Russia-Georgia conflict.

Russia wanted two OSCE field missions - one based in Georgia and the other South Ossetia - in an approach seen as supporting Moscow's recognition of South Ossetia and another breakaway region, Abkhazia.

State Department Spokesman Ian Kelly told reporters the United States deeply regrets the lack of consensus in Vienna, and praised the Greek team for offering a monitoring formula that would have avoided any pronouncement on South Ossetia's political or legal status.

"Unfortunately, Russia insisted on a monitoring operation structured to reflect Russia's recognition of South Ossetia's independence," he said. "We commend the Georgian delegation for its constructive approach, and are disappointed that Russia could not accept the Greek chairmanship's constructive, status-neutral solution."

Kelly said the United States views a monitoring presence in Georgia as essential and hopes Moscow, which also acknowledges a need for monitors, will eventually accept the Greek plan. In the absence of an agreement, the OSCE presence will end on June 30.

Russia is alone among European countries in recognizing the two breakaway Georgian regions. A Russian official at the Vienna talks said the Greek plan runs counter to what he termed "new international and legal realities" in the area.

State Department Spokesman Kelly declined to cast the Russian veto as a setback to hopes for better U.S. relations with Moscow under the Obama administration, and said he hoped Russia will reverse its disappointing stance.

Kelly reiterated "unwavering" U.S. support for Georgia's sovereignty and territorial integrity within its internationally-recognized borders, as did Vice President Joe Biden in a telephone talk with Georgian President Mikheil Saakashvilli on Thursday.

The White House said Mr. Biden welcomed the Tbilisi government's "measured" response to ongoing opposition protests, and stressed a need for both Georgia and Russia to exercise restraint and contribute to the stability of the separatist regions.