The Washington Post on Thursday and the Associated Press on Friday both reported that Retired Lt. Gen. Michael T. Flynn repeatedly phoned the Russian ambassador to the U.S. on the very same day the Obama administration expelled 35 Russian diplomats over election hacking. The allegation, made by an unnamed senior U.S. government official, raises the question of whether Flynn, President-elect Donald Trump’s pick for national-security adviser, was in violation of federal law with this alleged phone call. As author David Ignatius notes, the Logan Act prohibits U.S. citizens from any communication that is meant to influence a foreign government involved in disputes with the U.S. While the law has never seen a single person prosecuted, it could bring more scrutiny to a member of the Trump team that has already faced numerous questions over his ties with Russia. It’s not clear what Flynn allegedly spoke to Russian Ambassador Sergei Kislyak about on Dec. 29, but the timing raises questions. The White House announced harsh sanctions against Russian diplomats that day, ordering 35 out of the country on short notice and blacklisting top officials in the Russian security services. According to the AP, the Obama administration is aware of these frequent contacts between Flynn and the ambassador. During a Friday press call, Sean Spicer, the incoming White House press secretary, told reporters that Flynn’s initial contact with Kislyak was to wish him a Merry Christmas and a happy New Year to set up a future call between Putin and the president-elect.