Seoul: The South Korean won weakened markedly against the U.S. dollar Monday as U.S. President Donald Trump ordered a blockade of all ships entering or leaving the Strait of Hormuz after high-stakes peace talks with Iran failed to make a breakthrough. The won opened at 1,495.4 per dollar, down 12.9 won from the previous session's close.

According to Yonhap News Agency, the decline came after the United States and Iran concluded marathon talks in Islamabad Saturday (U.S. time) without reaching an agreement. The meeting was the first since a two-week ceasefire was reached last week. Following the breakdown in talks, Trump stated that the U.S. military would enforce a blockade on all vessels attempting to enter or exit the crucial waterway starting Monday, pushing global oil prices higher amid concerns over further supply disruptions.

The currency has shown heightened volatility in recent sessions, in line with developments in the Middle East conflict that began in late February, as rising oil prices have fueled concerns over inflation and a potential economic slowdown. Higher oil prices have pressured the won by increasing demand for dollars for crude imports as South Korea relies heavily on imports for energy.

The dollar index, which measures the value of the U.S. dollar against a basket of six major currencies, rose 0.4 percent to 99.04. Amid heightened tensions, the benchmark Korea Composite Stock Price Index (KOSPI) fell 0.66 percent to 5,820.13 as of 10 a.m. Monday, weighed down by heavy foreign selling.