WASHINGTON (NEXSTAR) - U.S. officials are "seriously concerned" amid political turmoil in South Korea. South Korean President Yoon Suk Yeol plans to soon lift the martial law he imposed after his country's parliament voted to reject military rule.  U.S. officials said Yoon did not inform them ahead of his decision to declare martial law. "We are watching these developments with grave concern," said Vedant Patel, the U.S. State Department's principal deputy spokesperson.  The conservative South Korean leader accuses his country's opposition party of sympathizing with North Korea. Just hours after his emergency declaration, protesters blocked the military from entering the country's parliament, and the Democrat-controlled body voted to immediately lift the military rule. "It is our hope and our expectation that any political dispute be resolved peacefully and in accordance with the rule of law," Patel said. The Pentagon said the developments have not changed any U.S. military positions or emboldened North Korea to act. "Of course, we're closely monitoring the situation, but I'm not aware of any force posture changes," said Pentagon Press Secretary Maj. Gen. Pat Ryder. Patel said there are also currently no changes to the travel advisory for South Korea. "We have no higher priority than the safety and security of our citizens," he said.  The U.S. ambassador to South Korea told U.S. citizens there to closely monitor local news sources.