This treaty, which is due to be adopted at a diplomatic conference in June, was first proposed by the American government in the early 1990s to formalise worldwide what American courts already often do: enforce foreign judgments in matters such as intellectual-property claims, contractual disputes and libel.

ECONOMIST: Stop signs on the web

Obama pushed at a joint news conference for continued diplomatic efforts, including negotiations and sanctions, intended to get Iran to comply with international safeguards against nuclear arms.

CNN: Obama, Netanyahu agree on preventing nuclear-armed Iran

One possible diplomatic payback to Spain would be hosting a second Middle East Peace Conference, similar to the one it hosted after the first Gulf War in 1991.

CNN: Analysis: Spain seeks wider role