Pakistan and Iran share a common border and some of the same challenges as well. In recent years, there have been a number of impediments to the relationship between the two states, most of them engendered by America’s antipathy to Iran and the regime of sanctions against it deployed by the US. Those sanctions have a spillover effect on Pakistan as it may find itself the subject of American sanctions if it is seen to breach those imposed by the US — a potent threat. It has already blighted the proposed gas pipeline between the two countries.

The World Health Organization declared a recent spread of polio to new countries to be an international public-health emergency, warning that it could undermine a lengthy and expensive eradication effort.