UNITED NATIONS — Abruptly discarding a week-old push to engage Russia and convince its leaders to end their war on Georgia, European and American diplomats are saying they will “cut to the chase” with a U.N. Security Council resolution that stresses the need for an immediate withdrawal of Russian forces from Georgian territory.

The move, which diplomats say is sure to result in a Russian veto, came as the North Atlantic Treaty Organization announced plans to strengthen its ties with Georgia. Russian officials responded by heaping scorn on the West’s newly confrontational tone and putting several new conditions on promises they made a week ago to withdraw their troops from Georgia.

The Georgian government yesterday accused Russia of taking 20 Georgian troops hostage, and Pentagon sources said Russian troops stole five military Humvees that America dispatched to assist the humanitarian efforts in Georgia.

The British ambassador to the United Nations, John Sawers, said Russian troops stopped a British military attaché in Georgia and turned him away from a Russian-controlled zone. Rather than withdrawing from Georgia, the Russian soldiers — whom Mr. Sawers said are now serving as “an army of occupation” — appear to be deepening their entrenchment in Georgia, according to press reports from the region.

The proposed council resolution, written in three succinct paragraphs by French diplomats and backed by America and the European Union, demands an immediate Russian withdrawal to positions held before the outbreak of hostilities. At a contentious emergency session of the Security Council yesterday, Russia’s ambassador to the United Nations, Vitaly Churkin, publicly announced that he “will not be able to support” such a text, even as Western diplomats pledged to put the proposal to a vote in the next few days.

A French U.N. ambassador, Jean-Pierre Lacroix, told reporters that in closed-door consultations, Mr. Churkin promised that Russia would complete its withdrawal from Georgia by August 22. Mr. Churkin immediately denied making such a statement and said the Russian withdrawal will largely depend on Georgian troop movements and on security arrangements within two separatist border regions of Georgia, South Ossetia and Abkhazia.

The proposed resolution includes a council “commitment” to “the independence and territorial integrity of Georgia within its internationally recognized borders,” a reference to the two regions, where Moscow-backed separatists are fighting for independence from Georgia. The resolution also “demands full and immediate withdrawal of the Russian forces to the lines held prior to the outbreak of hostilities” on August 7, as well as the return of Georgian forces to their “usual bases.”

But the proposal makes only a cursory reference to the rest of the six-point cease-fire plan proposed by President Sarkozy and signed by the leaders of Russia, Georgia, and the two breakaway regions. “Today, what is particularly important is that Russia makes good on its commitment to withdraw its forces,” Mr. Lacroix said. “Georgia has no immediate army potential anymore, so I don’t think that there is any reason why Russia has to maintain its troops any longer.”

As of yesterday, he added, there was no “credible” sign of Russia’s intention to withdraw.

Mr. Churkin said that as late as yesterday morning, the Russian and French presidents were negotiating by phone the details of a Security Council resolution that would incorporate all six points of what he called the “Medvedev-Sarkozy plan.” Then, all of a sudden, after what he said was pressure from Western countries, France and its allies proposed the new, abbreviated resolution, which Mr. Churkin called a “waste of time.”

America and its European allies weighed the idea of a shortened resolution for some time, a Western council diplomat said. Yesterday, after all the parties felt sure that Moscow had no intention of complying with the most urgent part of Mr. Sarkozy’s six-point plan, the withdrawal of Russian troops, “we decided to cut to the chase and put this in writing,” the diplomat, who spoke on the condition of anonymity, said. He denied that the new proposal was designed to force a Russian veto.

British and American officials reportedly pushed for a quick approval of Georgian and Ukrainian requests to join NATO during talks among the foreign ministers of the organization’s members in Brussels yesterday. “We said [Georgia] would eventually become a member of NATO alongside Ukraine, and that’s certainly the position that we will be advocating today,” the British foreign secretary, David Miliband, said, according to the Associated Press. But his colleagues from Italy and Germany reportedly urged caution, fearing Russian retaliation.