Ukraine's weakening economy is already a political liability for President Petro Poroshenko at home, but it now threatens to become yet another pressure point between Kiev and Moscow, according to IMF data released this week.

A deepening recession amid the five-month war with pro-Russian rebels has helped push Ukraine's GDP down sharply this year, while rising foreign borrowing has boosted government debt. As a result, Kiev is now perilously close to breaking the terms of a $3 billion Eurobond it sold to Moscow back in December, which set a limit on Ukraine's debt-to-GDP ratio of 60%. Breaching that could trigger default on Ukraine's other international bonds.

The IMF said this week the debt-to-GDP ratio could rise to about 67.5% by the end of this year and 74.5% next. For the moment, Kiev seems out of danger, but only barely, according to economists.

Ukraine's finance ministry doesn't publish the current debt-to-GDP ratio, and it didn't reply to a request for comment on current levels or the Eurobond terms. A rough calculation based on GDP figures the state statistics service provided, however, puts the ratio at 58% at the end of the second quarter, perilously close to the threshold.

For now, Russia's finance ministry says the ratio is below 60%, but officials say they're watching it closely.