resolves YES if the USA formally files whatever legal and diplomatic paperwork necessary to formally leave the defensive union. this will not resolve NO for an announcement of intention.
Hmm "Presently, there is no Supreme Court ruling on whether the President has the power to break a treaty without the approval of Congress; it remains unclear which branch of government is empowered by the Constitution to terminate a treaty, much less the procedure for doing so.[38] In practice, a president may terminate a treaty unilaterally if permitted by said treaty's terms.[39] President George W. Bush unilaterally withdrew the United States from the Anti-Ballistic Missile Treaty in 2002, six months after giving the required notice of intent,[40] but faced no judicial interference nor legal action.[39]"