NEWPORT, Wales (AP) — President Barack Obama says he’s skeptical that pro-Russian separatists and Russia’s government will abide by a cease-fire reached Friday.

Obama says he’s hopeful about the agreement between Ukraine’s government and pro-Russian rebels. But he says that based on past experiences he’s not sure separatists will follow through and that Russia will stop violating Ukraine’s sovereignty.

Obama is also crediting economic sanctions levied by the U.S and the European Union with bringing Russia to the table.

Obama commented at the close of a two-day NATO summit in Wales. Earlier Friday, NATO leaders agreed to form a new rapid response force to counter the threat of Russian aggression.

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