Pakistan, Jan. 16 -- The Trump administration's announcement that immigrant visa processing for 75 countries will be paused from January 21 has taken the world by surprise, exposing the fragility of relying on goodwill alone in great-power diplomacy.

The suspension applies specifically to immigrant visas-the legal avenues for permanent residency-for nationals of a broad list of countries that includes Pakistan, several South Asian neighbours and many African and Middle Eastern states. While non-immigrant categories such as tourist, student or business visas remain unaffected, the decision freezes the very pathways through which thousands of Pakistanis seek lawful settlement in the United States.

The official explanation from Washington ...