The leader of the NSA and Cyber Command on Tuesday said the U.S. alerted France to possible Russian involvement in their election.

Admiral Mike Rogers treaded carefully in testimony before the Senate Armed Services Committee, but said the U.S. knew of Russian activity before the emails of French president-elect Emmanuel Macron leaked onto the internet.

"If you take a look at the French elections — again unclassified hearing, not going to get into specifics — we had become aware of Russian activity," said Rogers.

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"We talked to our French counterparts prior to the announcement of the events that were publicly attributed this past weekend."

Friday evening, days before the Sunday's French election, emails and other files from the campaign Macron leaked onto the internet. No formal attribution has been made by either the U.S. or France. While Rogers alluded to the leaks, he stopped short of identifying Russia as the culprit.

Though he did not say if he contacted the French in regards to leaks or to other hacking, Rogers said he had told the French the U.S. was "watching the Russians penetrating some of your infrastructure" and offered U.S. assistance.

Trend Micro, a cybersecurity firm, reported before the election that it had found evidence that one of the same groups that attacked the systems of the Democratic National Committee also attacked the Macron campaign. It did not, however, mention what if any files the group spirited access to.

Some of the files within the releases had a name written in Russian within their metadata listing the last person to open them. File metadata is easy to manipulate and is considered weak evidence.

The files also appear to have been originally uploaded by someone with a German free webmail account; Russian groups have been known to use free webmail accounts from Europe in the past.