Sentence:  Paradoxically , the same week in which Senator McClellan was attempting to extend the anti-trust act to labor in transportation , the Civil Aeronautics Board was <WSD>assuring</WSD> the airlines that if they met in concert to eliminate many costly features of air travel , the action would not be deemed a violation of the anti-trust act . 
Meaning of the word marked with <WSD> tags:  inform positively and with certainty and confidence