(CNN) Embattled White House national security adviser Michael Flynn resigned Monday night.

His resignation came after reports that the Trump administration was warned last month that Flynn misled administration officials regarding his communications with the Russian ambassador to the United States and was potentially vulnerable to blackmail by the Russians, a person familiar with the matter told CNN.

Read the full text of Flynn's resignation letter below:

February 13, 2017

In the course of my duties as the incoming National Security Advisor, I held numerous phone calls with foreign counterparts, ministers, and ambassadors. These calls were to facilitate a smooth transition and begin to build the necessary relationships between the President, his advisors and foreign leaders. Such calls are standard practice in any transition of this magnitude.

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