nuclear arms treaty violation

I'm not talking about Russia or China or Iran.  I am referring to Trump, who says he wants to take the US out of the medium range nuclear missile treaty, a treaty that was approved by the US Senate, per the Constitution's requirements.

How is it that the president - of any party - can unilaterally abrogate a valid treaty, lawfully approved by the Senate?  That would constitute an unconstitutional act, and present a marked similarity to despots and strong men actions.  We should push back.

And, since a treaty, once approved by the Senate, becomes the law of the land, by taking the US out of this treaty - or any treaty - is a violation of the law.  Presidents are supposed to see that the laws are faithfully executed.

Why aren't Senators asserting their separate but equal branch authority by rejecting this action by Trump?  If there are violations by Russia - would not be a surprise - then we should engage the legislative branch and the State Department to deal with it.  If an abrogation of the treaty is warranted, then the Congress should authorize it.

Why isn't the press asking these questions?