SEOUL, South Korea — South Korea’s Constitutional Court overturned the impeachment of Prime Minister Han Duck-soo, reinstating the nation’s No. 2 official as acting leader Monday while not yet ruling on the separate impeachment of President Yoon Suk Yeol over his shocking imposition of martial law in December.

Many observers said the 7-1 ruling in Han’s case did not signal much about the upcoming verdict on Yoon because Han wasn’t a key figure in imposing martial law. But the ruling could still embolden Yoon’s staunch supporters and ramp up their political offensive on the opposition.

Speaking with reporters after his reinstatement, Han thanked the court for what he called “a wise decision” and promised to focus on tackling “urgent matters,” including a fast-changing global trade environment, in an apparent reference to the Trump administration’s aggressive tariffs policy.

South Korea has been in political turmoil since Yoon, a conservative, declared martial law Dec. 3 and sent hundreds of troops to the liberal opposition-controlled National Assembly and other places in Seoul. Yoon’s decree lasted only six hours; enough lawmakers managed to enter an assembly hall where they quickly voted down the decree.

The assembly impeached Yoon on Dec. 14, alleging that he violated the constitution and other laws by suppressing assembly activities and trying to detain politicians.

Yoon’s impeachment made Han acting president until he was impeached in late December.

The unprecedented, successive impeachments that suspended the country’s top two officials intensified domestic division and deepened worries about South Korea’s diplomatic and economic activities.

A major trigger for the opposition’s push to impeach Han was his refusal to fill three vacant seats at the Constitutional Court’s nine-member bench.

That was a highly explosive issue because the court needed support from at least six justices to approve Yoon’s impeachment and filling its empty posts could make such a decision more likely.

After Han was suspended, his successor as acting president, Choi Sang-mok, appointed two new justices but left the ninth seat vacant.

Han was also accused in the impeachment motion of abetting Yoon’s martial law declaration and obstructing efforts to open independent inquiries into Yoon’s alleged rebellion in connection with his martial law decree.

On Monday, seven of the Constitutional Court’s eight justices ruled to overturn or dismiss Han’s impeachment. They ruled that his alleged actions weren’t against the law or weren’t serious enough to remove him from office or his impeachment motion didn’t even meet a required quorum when it passed thorough the assembly. One justice upheld Han’s impeachment.

The main liberal opposition Democratic Party expressed regret over the court’s decision to quickly reinstate Han and urged it to dismiss Yoon. Yoon’s office welcomed Monday’s ruling, saying it shows again the opposition’s repeated uses of impeachment motions were a “reckless, malicious political offensive.”

Observers had predicted that the Constitutional Court would rule on Yoon’s case in mid-March, but it hasn’t done so, sparking varied speculation on possible reasons.

“Today’s verdict will give hope to Yoon’s supporters for a similar fate and hope for Yoon’s opponents for his ouster,” said Duyeon Kim, a senior analyst at the Center for a New American Security in Washington. “But it’s too soon to predict the court’s verdict on Yoon because the specific details of both cases and allegations are different.”

Kim said the reinstatement of Han, a career bureaucrat, will bring more stability to South Korea compared to when his powers as acting president were suspended.