U.S. special counsel Robert Mueller’s investigators are questioning Jared Kushner’s contacts with Israeli officials during the presidential transition over a United Nations resolution that condemned Israeli settlement construction.

The investigators have asked witnesses about the involvement of Kushner, a senior White House adviser and the Jewish son-in-law of President Donald Trump, in discussions with foreign leaders in an attempt to block the UN Security Council resolution which passed 14-0 on Dec. 23, 2016, the Wall Street Journal reported late Tuesday.

The Obama administration angered many in the pro-Israel camp by withholding its veto and abstaining from voting on the resolution, which called Israeli settlements “a flagrant violation of international law” that damage the prospects of a two-state solution to the Israeli-Palestinian conflict.

The questions have come as part of Mueller’s probe of Russia’s alleged meddling in the 2016 U.S. presidential elections.

Israeli officials had asked the incoming Trump administration to intervene to help block the Security Council’s late December vote, according to the Wall Street Journal.

Trump discussed the resolution in a phone call with Egyptian President Abdel Fattah Al Sisi, whose government had drafted a version of the resolution, according to the Journal. Following the conversation Egypt called for the vote to be delayed, but the resolution passed a day later.

Israeli officials reached out to Trump transition leaders such as Kushner, as well as chief strategist Steve Bannon, to stop the resolution, the Journal reported, citing unnamed people briefed on the discussions.

The sources said that Mueller’s investigators have asked about Kushner’s role in arranging meetings or communication with foreign leaders during the transition, part of his broad mandate to examine issues that come up during the Russia investigation, according to the Journal.

Kushner is being investigated for omitting foreign contacts from his application to obtain a security clearance. He has since updated the form to include more than 100 contacts with more than 20 countries, according to the newspaper, and has not yet received his security clearance.