Japanese measures to impose tighter export regulations on three chemicals vital to South Korea's manufacturing sector formally went into effect on Thursday, raising the prospects of the two countries sliding into a protracted conflict — though the severity of the measure's economic impacts remains unclear.

The enhanced licensing requirements applied by the trade ministry to Japan's third largest trading partner restrict exports of three chemicals that are integral components in the manufacture of high-tech products such as semiconductors, smartphones and television displays.

South Korea's economic policy chief said Thursday he would not rule out direct countermeasures against Japan if Tokyo maintains its restrictions on the exports for an extended period.