Implementation urged after deal reached on cessation of hostilities in Syria

Kerry acknowledged that the Munich meeting produced commitments on paper only. He and Russian Foreign Minister Sergei Lavrov agreed that the real test would be whether all parties to the Syrian conflict honor those commitments.

Earlier this month, UN-mediated negotiations between the Syrian government and opposition groups in Geneva, Switzerland, have been delayed to Feb. 25.

Lavrov, in a joint news conference with Kerry, said that it would be a "complicated task" to finally achieve a cease-fire in Syria.

"We hope the agreements reached will be reorganized into practical steps," Lavrov said before a meeting with Saudi Foreign Minister Adel bin Ahmed Al-Jubeir in Munich, according to Russia's RIA news agency.

According to the agreement reached by ISSG members, the cease-fire in Syria will not apply to groups designated as terrorists.

Lavrov told reporters that Moscow's air force would continue its airstrikes against targets of the Islamic State and Al-Nusra as the agreement permitted.