PECHORY, Western Russia -- In 1920 Lenin was in a tight spot. The British had occupied Baku and the French were attacking from Odessa; White armies in Siberia and Kiev were headed for Moscow; and Estonia, a nation barely one year old, was refusing to fall to the attacking Red Army.


Something would have to give -- Lenin's young government needed breathing space. So the Bolsheviks signed a treaty in the Estonian university town of Tartu to end Soviet-Estonian hostilities.


Today, the Estonians are pushing the little-known Tartu treaty -- which redrew the Estonian-Russian border deeper inside Russian territory -- at diplomats and journalists the world over. And as Russian troops pour out of the Baltics, emboldened Estonians are stepping up a campaign to force Russia to honor the terms Lenin accepted and hand over the Pechory region, a 2,335 square kilometer patch of forests, lakes, farms and a couple of Russia's most ancient churches and fortresses.


Russia undid the Tartu treaty and got Pechory back as part of the Red Army's occupation of Estonia during World War II. The Bolshevik government, in what was then little more than symbolism, rewrote the administrative borders dividing the Estonian and Russian Soviet socialist republics to put Pechory squarely in Russia; today that line is where post-Soviet Russia draws the border.


Estonians grudgingly surrender their passports to Russian border guards at this de facto international frontier, but they insist on calling it "the control line." The real border, they say, is the one drawn by the Tartu treaty, and they have written that border into their new constitution, adopted in 1992. Under Estonian law, Pechory is Estonian soil.


Getting Pechory back would increase the area of West Virginia-sized Estonia by 5 percent; and so barely a day goes by now when an Estonian national leader does not hold forth on the Tartu treaty. Once Russian troops have left Estonia -- they should be gone in the next few days -- Pechory could quickly come to dominate Estonian-Russian relations.


Here in Pechory (or Petseri in Estonian), a town of 12,000 and the region's capital, the Tartu treaty is unpopular. A survey three years ago found that 87 percent of Pechori's population was opposed to leaving Russia for Estonia; and although Estonia's economy has since left Russia's mired in the mud, most locals say few minds have changed.


"Estonia has no right to claim this land, it is ancient Russian land," said Svetlana Derdyesova, 41, the editor of Pechorskaya Pravda, the region's twice-weekly paper.


At the Pechory Monastery -- a church-fortress built upon sandstone caves that has never closed in its 541-year history and remains a jewel of the Russian Orthodox Church -- priests preferred not to comment publicly on such worldly matters.But privately they say Pechory is and ought to be Russian. It is not easy for them to stay neutral: The monastery often comes up in discussions of the border. The Estonians claim, with some justification, that they took better care of the monks than the Russians would have. The Tartu treaty put the monastery under Estonian rule from 1920 until the Soviet occupation in 1939 -- putting it out of Stalin's reach at the height of his anti-church policies.


Such arguments move few Russians, however.


"Estonia's insistence that Pechory belongs to them is not smart. Maybe I'm being undiplomatic, but it's dumb," said Victor Zvonkov, vice governor of the Pskov region -- where most of the disputed Pechory territory is located.


"For all these hundreds of years, Pechory has belonged to Russia. Then, for 20 years, according to a treaty wrung from the war-weary government of a state that doesn't even exist anymore, it was Estonian. That's not a serious claim."


Zvonkov and other pro-Russian Pechorians try to trump the Tartu treaty with the earlier treaty of Nystadt, which Peter the Great's Russia signed with Sweden in 1731, ending the 21-year Great Northern War.


"Under the Nystadt treaty, we owned all of Estonia. But we don't go referring to that treaty, do we?" Zvonkov said.


The Estonians feel that the Russian government's position boils down to might-makes-right: The Russians simply ignore the Tartu treaty, and have not even bothered to officially denounce it. "The Russian Federation asserts that the illegal annexation of territory by force has redefined the border," complained the Estonian Foreign Ministry in one of a flurry of recent statements.


Estonia wants to see the dispute mediated by the Hague, or the UN, or by just about anyone who can bring the Russians to the table. But last week the Russians, in a demonstration of their resolve to ignore the matter, began marking off the existing border with two-foot wooden posts.


The Estonian government, fuming over "illegal" moves to "unilaterally demarcate a disputed border," has demanded that Russia halt work. Baltic newspapers carry day-by-day accounts of how many posts have gone up, complete with analyses of how bad weather and tangled thickets are influencing the speed of post-hole diggers.


"The international community has hopefully predicted improvement in Russian-Estonian relations," complained an Estonian government statement, but "the present situation raises the question whether Russia actually wishes to normalize relations with Estonia at all."


In Pechory, pro-Russian officials counter that Estonians have also flouted the law when it has suited them. Under Estonian law, the 29,000 residents of the Pechory region are automatically eligible for Estonian citizenship if they lived there before the occupation. Locals say the Estonian government has actively recruited citizens in Pechory, and the Estonian Foreign Ministry does not deny such charges.


"This citizen recruiting is not exactly proper," said Vitaly Kustyev, assistant chief administrator of Pechory and the Pechory region. "It's illegal. If I were to go to Mexico and start giving out Russian passports, as part of a plan to claim as Russian territory a portion of Mexico, how do you think I'd be received? I'll tell you how: I'd be deported."