Trump has already ended that policy.
he forgot to tell a lot of my buddies about it. Because they're still stuck in Afghanistan and Iraq.
However, this misses the point that the goal of the proposed institute is to:
> ... promote an approach to the world based on diplomacy and restraint rather than threats, sanctions, and bombing.
Unfortunately, the current negotiation tactics being pursued against, say, Iran, do not fall under this new style of diplomacy. I'm sure other examples may come to mind.
That's really a continuation of the policies of the prior two presidents (maybe more, I just don't remember one way or the other).
He didn't, the Syrian Arab Army and Russia did (and the Syrian Defense Forces, to an extent).