JARIASHENI, Georgia — Marked in places with barbed wire laid at night, in others by the sudden appearance of green signs declaring the start of a “state border” and elsewhere by the arrival of bulldozers, the reach of Russia keeps inching forward into Georgia with ever more ingenious markings of a frontier that only Russia and three other states recognize as real.
But while dismissed by most of the world as a make-believe border, the dirt track now running through this tiny Georgian village nonetheless means that Vephivia Tatiashvili can no longer go to his three-story house because it sits on land now patrolled by Russian border guards.
That track marks the world’s newest and perhaps oddest international frontier — the elastic boundary between Georgian-controlled land and the Republic of South Ossetia, a self-proclaimed breakaway state financed, defended and controlled by Moscow.
Mr. Tatiashvili’s troubles started early in the summer when earth-moving equipment turned up without warning and started digging a wide track through an apple orchard and a field of wildflowers on the edge of the village. He was out at the time, so he avoided being trapped.
There is no fence or barbed wire, but Mr. Tatiashvili does not dare to cross the track to visit his house for fear of being arrested, as his elderly neighbor was, by Russian border guards.
“It is too dangerous for me to go home,” he said, complaining that the boundary has become so mobile that nobody really knows its final destination. Mr. Tatiashvili now lives in his brother’s house, away from the border in the village center.
The destitute mountainous area of South Ossetia first declared itself independent from Georgia in 1990, but nobody outside the region paid much attention until Russia invaded in August 2008 and recognized South Ossetia’s claims to statehood. With that, the territory joined Abkhazia in western Georgia, the Moldovan enclave of Transnistria and eastern Ukraine as a “frozen zone,” an area of Russian control within neighboring states, useful for things like preventing a NATO foothold or destabilizing the host country at opportune moments.
The leader of South Ossetia, Leonid Tibilov, has said he plans to hold a referendum like the one in Crimea in 2014 on whether to request annexation by Russia.
But even without a referendum, the nominally independent country is already Russian territory in all but name. It has its own small security force, but its self-declared frontiers are mainly guarded by Russia’s border service, an arm of the Federal Security Service, the post-Soviet version of the K.G.B. It houses three Russian military bases with several thousand troops and, with no economy beyond a few farms, depends almost entirely on Russian aid for its survival.
The green border signs that first appeared last year and now keep popping up along the zigzagging boundary warn that “passage is forbidden” across what is declared to be a “state border.” Which state, however, is not specified, though locals are in no doubt about its identity.
“Russia starts right here,” Mr. Tatiashvili said, pointing to the freshly dug track that separates his house from Georgian-held land.
“But who knows where Russia will start tomorrow or the next day,” he said. “If they keep moving the line, we will one day all be living in a Russian-Georgian Federation.”
One of the new signs — written in English and Georgian — is just a few hundred yards from Georgia’s main east-west highway, and it puts a short part of an oil pipeline from Azerbaijan to a Georgian port on the Black Sea within territory controlled by Russia.
So tangled is the dispute over what land belongs to whom that each side has its own definition of the line. Russia and South Ossetia insist it is a border like any other — Venezuela, Nicaragua and Nauru also recognize it — while Georgia calls it “the occupation line.” The European Union, which has around 200 unarmed police officers in Georgia to monitor the agreement that ended the 2008 Russian-Georgian war, also says there is no actual border, only an “administrative boundary line.”
Kestutis Jankauskas, the head of the European Union Monitoring Mission in Georgia, said it was hard to know where this boundary line exactly runs. It was never recognized or agreed upon, and its location depends on which maps are used. Russia, he said, is using a map drawn by the Soviet military’s general staff in the 1980s.
It demarcates what in the Soviet era was an inconsequential administrative boundary within the Soviet Socialist Republic of Georgia but what is now hardening into a hazardous frontier.
The fitful movement of the boundary seems to be driven mostly by Russia’s desire to align what it sees as a state border with this old Soviet map. So far, the movement has always been forward, often by just a few yards but at other times by bigger leaps.
Because the line is so uncertain and, in many places, still completely unmarked, Georgian villagers sometimes find themselves on the wrong side and under arrest by Russian border guards or local security officers.
To help get people out of detention, recover cattle that have strayed into Russian-controlled land and settle quotidian disputes like who owns which apple trees or vineyard, Europe’s monitoring mission organizes a monthly meeting of Georgian, Russian and South Ossetian officials.
As happened when the two pro-Russian regions of eastern Ukraine declared themselves independent states in 2014 and said they would like to be absorbed by Russia, President Vladimir V. Putin has mostly feigned ignorance of what his country’s surrogates are up to in Georgia.
Asked in April about South Ossetia’s plans to hold a referendum on joining Russia, Mr. Putin suggested that Moscow was mostly a bystander. But if South Ossetia wants to hold a referendum, Mr. Putin said, “we cannot resist it.”
While Russian military, border and diplomatic personnel have poured into South Ossetia, the local population of Ossetians — an ethnic group whose language is distantly related to Persian — has steadily drifted away, shrinking by around half from a prewar level of roughly 70,000. An ethnic Georgian population of around 25,000 that used to live there has long since fled.
Like Israeli settlements in occupied Palestinian territory, the border markings deep into what Georgia insists is its territory are slowly creating “facts on the ground” that, no matter what the international community might think, are a reality that everyone has to deal with, particularly residents.
Elizbar Mestumrishvili, 75, a farmer who lives next to Mr. Tatiashvili’s now-marooned house, can still get to his home, as it lies on the Georgian side of the new dirt track.
But he is wary of going to the bottom of his garden, which lies within a 60-yard frontier zone that Russian and South Ossetian security officers claim the right to patrol. Pointing to a row of vines drooping with plump grapes, he said it was unwise to walk any farther because “they might come and set up a border post.”
The so-called borderization of a previously vague administrative boundary created political headaches for Georgia’s government ahead of parliamentary elections on Oct. 8. It still won the election but had to fend off attacks from rivals who said it had responded too meekly to Russia’s “creeping annexation.”
When it defeated supporters of former President Mikheil Saakashvili in elections four years ago, a coalition led by Georgian Dream, a party set up by an enigmatic billionaire, pledged to reduce tensions with Russia, which loathed Mr. Saakashvili. Instead, Russian border guards have moved deeper into Georgian territory.
“There is no improvement. I would say the opposite,” Prime Minister Giorgi Kvirikashvili said in an interview. “Unfortunately, Russia never appreciates when you concede or make a step forward or compromise. They always take it for granted.”
All the same, he insisted that even though his government had no intention of repeating Mr. Saakashvili’s disastrous 2008 attempt to confront Russia militarily, the border will not last.
“It has no prospect,” he said. “They are trying to build this border, these fences inside our country. We think it is temporary.”