MOSCOW (AP) — Russian President Vladimir Putin called President Barack Obama on Friday to discuss a diplomatic solution to the Ukrainian crisis, while Ukraine’s fugitive leader urged a nationwide referendum that would serve Moscow’s purpose of turning its neighbor into a loosely knit federation.

The statement from Viktor Yanukovych, the former Ukrainian president who fled to Russia last month after three months of protests, raised the threat of more unrest in Ukraine’s Russian-speaking eastern provinces, where many resent the new Ukrainian government.