A sign of common cause in Geneva.

Russia, Ukraine, the U.S. and EU agree to an immediate halt to violence in Ukraine -- where Western powers believe Russia is fomenting a pro-Russian separatist movement.

U.S. President Barack Obama welcomes the move.

(SOUNDBITE) (English) U.S. PRESIDENT BARACK OBAMA SAYING:

"There is the possibility, the prospect, that diplomacy may de-escalate the situation."

He told White House reporters it will take a few days to see if Russia embraces the agreement.

(SOUNDBITE) (English) U.S. PRESIDENT BARACK OBAMA SAYING:

"The question now becomes: will, in fact, they use the influence they've exerted in a disruptive way to restore some order so that Ukrainians can carry out an election and move forward with the decentralization reforms that they've proposed?"

And he has reservations.

(SOUNDBITE) (English) U.S. PRESIDENT BARACK OBAMA SAYING:

"My hope is that we actually do see follow through over the nex