KIEV, Ukraine — Ukraine’s fourth-richest man has a plan he says will help end the war with pro-Moscow rebels in the country’s volatile east. He proposes building a $136 million fence along the porous border with Russia to prevent tanks, artillery and mercenary soldiers from entering Ukraine to join the separatists’ ranks.

Ihor Kolomoisky is willing to put up some of his own fortune to get it done within the next six months.

An oligarch who Forbes estimates is worth about $1.8 billion, Kolomoisky recently pitched the seemingly far-fetched scheme to Ukraine’s newly elected president, Petro Poroshenko, also a Ukrainian oligarch, worth some $1.3 billion. Kolomoisky’s vision is a 1,200-mile fence constructed with high-strength steel and an electric current running through it, which would include a parallel moat system and layers of barbed wire as an added precaution.

Whether or not Poroshenko takes up Kolomoisky’s fence plan — and there is little sign such a project is feasible — the fact that Ukrainian oligarchs are still so prominent in Ukraine politically and economically poses serious challenges to the strife-torn country.

Many of the protesters who gathered in central Kiev’s Independence Square last year to demonstrate against then-President Viktor Yanukovich’s refusal to sign an association agreement with the European Union were taking a stand against entrenched and corrupt elites in politics and business.

But with a violent uprising in parts of the mostly pro-Russian east, the prospects for reducing the power of entrenched elites in Ukraine appear to have diminished. In order to for the country to achieve real change, “the prominence of Ukraine’s oligarchs in the economy must be decreased,” said Pavlo Sheremeta, minister of economic development and trade, in a recent televised interview.

Yet the influence of the oligarchs has likely gotten stronger. The debate over a fence is far from the first time Kolomoisky — Kiev’s appointed governor of the industrial region of Dnipropetrovsk — has offered his millions to help Ukraine fight the pro-Kremlin separatist rebels. Shortly after they took over government buildings and police stations in April throughout his neighboring eastern regions of Donetsk and Luhansk, the banking magnate offered bounties of up to $10,000 for the capture of the movement’s leaders and $1,000 for each rebel Kalashnikov. He is bankrolling paramilitary groups fighting alongside the national guard and has paid for gasoline to fuel Ukrainian military vehicles.