"Russia and Ukraine are well off the scale, and appear most vulnerable to dollar strength," which exacerbates their dollar-denominated external debt burdens, Martin said.
Geopolitical tensions between Russia and Ukraine weighed on their economies in 2014 and continue to drag their currencies. Since last August, the Ukrainian hyrvnia has weakened by over 100 percent, while Russia's ruble weakened 90 percent, with Western sanctions and the price collapse in oil – one of Russia's main exports – adding pressure.
Ukraine's dollar-denominated external debt is around 79 percent of gross domestic product (GDP), according to Martin. Russia's dollar-denominated debt of around $38 billion is perhaps less worrying given its over $2 trillion economy, according to data from Wells Fargo. A large portion of its $600 billion in corporate debt is denominated in dollars however, raising the risk companies will fault even though the government probably won't, according to Reuters.
Markets are clearly worried, despite news of the ceasefire: the yield on Ukraine's two-year government bonds, the longest available, is at 17.5 percent, according to Thomson Reuters data; the spread on Ukraine's five-year U.S. dollar-denominated credit default swaps are quoted at around 2,500 basis points and has widened by 18.2 percent in the last month, according to Markit data.
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"Russia is not as vulnerable," said SocGen's Chattelier. And the spreads on its debt reflect the weaker concerns.
The yield on Russia's government bonds is 13.84 percent for the two-year and 13.6 percent for the five-year; the spread on the five-year dollar CDS has been narrowing and is currently quoted at around 500 basis points.
Turkey, Chile and Peru are also at risk given large dollar-denominated debt burdens and currencies that have held up against dollar strength thus far, Martin said.
"Turkey is in a difficult situation. Falling oil prices help reduce its current deficit and inflation, but a further strengthening of the dollar would drive up the cost of servicing its debt," said SocGen's Chattelier.
By contrast, Brazil should be out of the danger zone as its currency already fell "a long way", Martin said. The Real has weakened by nearly 30 percent since early September.