The U.S. secretary of state also said he will use talks Sunday in Switzerland to assure his interlocutors that a letter from GOP senators on the validity of a nuclear deal with Iran carries no weight.
The foreign ministers of the four signatories to the Minsk cease-fire agreement met in Paris to discuss the fighting in Ukraine. Kiev worries that the separatists' next target will be Mariupol.
U.S. and Iranian delegates are trying to settle on the framework for an accord on the future of Iran's nuclear program. Not everyone is impressed with this nuclear diplomacy.
Secretaries of state and other top officials sometimes make personal stops while traveling on official business. It's permitted, though it sometimes raises eyebrows and questions of cost.
The Obama administration was criticized for not sending a high-ranking official to a unity rally in Paris. The British, German, Israeli and Palestinian leaders were all at the march.