The upcoming meeting between U.S. President Donald Trump and Xi will be followed by a Putin-Xi summit. Will there be scope for triangular diplomacy?

The U.S. and Chinese presidents are scheduled to gather in Beijing on Thursday and Friday amid a packed week of diplomatic meetings.

The US president is due to visit China from Wednesday, at a time when he is embroiled in the conflict with Tehran, of which Beijing is a partner. Meanwhile, the oil and gas crisis…