Kirill Dmitriev: US, Ukraine, Russia near diplomatic solution. Budapest summit postponed, not canceled. Dmitriev in US for planned visit. US sanctions on Russian oil, impact limited. Zelenskyy shifts to battle-line talks. Russia seeks final solution, not cease-fire. Cease-fire can be broken, working to end conflict. Trump spoke to Putin, planned Budapest meeting, later canceled. Dialogue depends on Russia’s interests being respected