Ukrainian President Volodymyr Zelenskiy has dismissed two judges from the Constitutional Court, deepening a feud with the top court over anti-graft reform.

In a March 27 decree, Zelenskiy removed Constitutional Court Chairman Oleksandr Tupytskyi and another judge, Alexander Kasminin, for continuing to “threaten Ukraine’s independence and national security.”

Both judges were appointed by pro-Russia former President Viktor Yanukovych, who was ousted in 2014 following the Euromaidan protests.

The decree comes after the Constitutional Court in October struck down some anti-corruption legislation and curbed the powers of the National Anti-Corruption Agency (NAZK). The court decision dealt a blow to reforms demanded by the West and threatened to impact lending from the International Monetary Fund.

In response to the court ruling, Zelenskiy vowed to reverse its decision and continue with his anti-graft reform agenda.

In the decree, Zelenskiy invoked a parliamentary decision calling Yanukovych’s rule from 2010 to 2014 a “usurpation of power.”

“Certain judges of the Constitutional Court of Ukraine appointed by Viktor Yanukovych, by continuing to exercise their powers, threaten Ukraine’s independence and national security, which violates the constitution, human and civil rights, and freedoms,” the decree states.

It’s unclear if Zelenskiy’s decree is valid, potentially setting off a fresh dispute with the powerful court.

In December, Zelenskiy issued a decree suspending Tupytskyi, who is facing a preliminary investigation over suspected witness tampering and bribery.

The Constitutional Court then ruled that the president had exceeded his powers, in what Tupytskyi called an attempted “constitutional coup” against the judges.

According to Ukraine’s constitution, constitutional judges can only be dismissed by a vote of two-thirds of its 18 members.

With reporting by AFP, RFE/RL’s Ukrainian Service, and the Kyiv Post