Following his meetings at the White House, Ukrainian President Volodymyr Zelensky said his country and its allies were "already working on the concrete content of the security guarantees". There is a wide spectrum of options to be considered, writes Frank Gardner, ranging from "boots on the ground" to the threat of crippling economic sanctions on Russia's oil exports. The US has made clear that Ukraine won't become a member of Nato in the foreseeable future, but the military alliance could support the country in other ways. But the question remains over what Russia is prepared to accept - and whether Moscow should have a say in the matter at all.

A concert by ultra-nationalist Croatian singer Thompson has exposed divisions deep within the Balkan country. The performer led the crowd - including MPs from the governing HDZ party - in a chant associated with the Nazi-allied Ustasha regime that ruled Croatia during World War Two, outraging opposition parties. But was it a "neo-fascist Croatian Woodstock" or just patriotic, anti-establishment fun?