The suspension of Ukraine's domestic spy chief has laid bare Kyiv's battle away from the front lines to purge its powerful security agencies of collaborators and Russian agents.
President Volodymyr Zelenskyy suspended Security Service of Ukraine (SBU) chief Ivan Bakanov, a childhood friend, and top state prosecutor Iryna Venediktova.
The Ukrainian leader cited dozens of cases of collaboration by members of their agencies in Russian-occupied Ukraine.
Mr Zelenskyy singled out the case of senior SBU official Oleh Kulinich, appointed under Mr Bakanov to focus on Russian-annexed Crimea, who was arrested on suspicion of treason on Saturday.
He had been sacked shortly after Russia's February invasion.
In a speech to the nation, Mr Zelenskyy hailed the operation against Mr Kulinich as part of a process of "self-purification".
He said prosecutors and law enforcement officials had opened 651 cases into suspected treason and collaboration, and said more than 60 people from Mr Bakanov's and Ms Venediktova's agencies were now working against Kyiv.
Kyiv-based analyst Volodymyr Fesenko said Mr Kulinich's arrest was the last straw after suspicions of treason had swirled around some of his regional chiefs.
"The decision on Bakanov was forced," he said.
"This is a crisis decision. They need to bring in order, to purge the SBU and search for … agents. Not only in the SBU, of course, but the SBU is critically important."
The SBU is the main agency in charge of counter-espionage and domestic security.
The sprawling organisation emerged out of the Soviet-era KGB and has been the subject of a reform push in recent years.
Treason rumours continue to plague security agency
Mr Bakanov, a security outsider with a background in show business, was appointed to head the SBU in 2019.
He was one of an array of new faces who rose to prominence after Mr Zelenskyy, a former comedian, won the election earlier that year.
One of the enduring questions of the first phase of the war is why the southern region of Kherson fell to Russia so quickly in contrast with the fierce Ukrainian resistance near Kyiv that forced Moscow to abandon its push for the capital.
"It was obvious there was treason in Kherson region," Mr Fesenko said.
"That there were agents is obvious. Now there will be tough counter-intelligence action and outing of these agents.
Mr Zelenskyy announced the sacking of SBU regional head for Kherson, Serhiy Kryvoruchka, and another SBU general during a speech on March 31.
"Now I don't have time to deal with all the traitors but gradually they will all be punished," Mr Zelenskyy said at the time.
Constitutional and policy expert Bohdan Bondarenko said the problem of collaborators and agents had been more acute back in 2014 when Russia annexed the peninsula of Crimea and backed a separatist insurgency in the east.
"Now it's certainly smaller, but it remains," he said, citing Kherson as an example.
Mr Bondarenko said he believed Sunday's political shake-up was likely intended to demonstrate to the public that Mr Zelenskyy was taking action against Russian infiltration.
He said the move would consolidate Mr Zelenskyy's power.
"This information about internal checks and defections … looks like a formal grounding to go to the public and say 'look, there is a problem, and I am trying to solve it this way'."
Ukraine's first lady to meet with Jill Biden
The US State Department announced it would continue providing intelligence to Ukraine despite Mr Zelenskyy's firing of the two officials.
Ukraine's first lady Olena Zelenska arrived in the US on Tuesday. She will deliver a speech to US Congress on Wednesday.
Ms Zelenska met with Secretary of State Antony Blinken in Washington, the first of a series of high-profile appearances that will include a meeting with her US counterpart, Jill Biden.
ABC/AP/Reuters
