The two leaders were close to agreement not only on a territorial principle that most foreign governments endorse but also on the tricky issue of Jerusalem.
Some claim that the tricky issues that stand in the way of a multilateral deal can be more easily resolved when only two countries are sitting at the table.
He couldn't include online games, for example, since measuring their revenue is still a tricky issue.
File locking is a very tricky issue and race conditions abound.