Ukraine's president and top security brass discussed ways to prevent leaks of military information at a meeting on Friday, Kyiv said, after secret documents detailing Western help for Ukraine reportedly ended up online.
A Saturday Wall Street Journal report claimed that the leaked documents also include "intelligence on internal matters with a variety of nations, including allies Israel, South Korea, and the UK."
Justice Department spokespeople declined to give a comment to the WSJ Saturday on the investigation.
The New York Times reported on Thursday that the Pentagon was investigating how documents about plans to build up Ukrainian forces before their planned counter-offensive against invading Russian forces were posted on social media channels last week.
A statement about the meeting issued by the Ukrainian president's office did not say a leak had occurred. It also did not refer to a New York Times report that said documents about US and NATO plans to build up the Ukrainian military had been leaked online.
"The participants of the meeting focused on measures to prevent the leakage of information regarding the plans of the defense forces of Ukraine," a presidency statement said, detailing other topics that participants also discussed.
Israel's recent round of cyber attacks
The website of one of Israel's largest cyber-security companies, Check Point, was taken down by a group of hackers calling themselves "Anonymous Sudan" on Tuesday afternoon.
Earlier in the day, the websites of multiple major universities in Israel were also attacked by the same group and were down for several hours.
Among the websites unavailable for browsing were the sites of Tel Aviv University, the Hebrew University of Jerusalem, Ben-Gurion University of the Negev, Haifa University, Weizmann Institute of Science, Open University of Israel and Reichman University.
Reuters contributed to this report.