Stephen Collinson: “President Donald Trump’s Iran entanglement is beginning to resemble a visual illusion known as the Penrose stairs, which endlessly climb and descend but always end up in the same place.”“The predicament is of Trump’s own making after he launched a war that never promised a definitive exit and crafted a memorandum of understanding that failed to address the reasons for the conflict.”“Does he escalate the war — at a potentially high human, economic and political cost — to try to shatter a new status quo that hands Iran the most leverage? Or does he try to revive a flawed ceasefire that pays Iran billions just to talk?”