Ukraine pressed ahead with a military offensive against pro-Russia militants in the east Wednesday, declaring early successes even as its top diplomat agreed in Berlin to work with his Russian counterpart toward a new cease-fire.

The government's claims of progress, two days after suspending a previous cease-fire, reflect a significant increase in the military's numbers and fighting ability in recent weeks.

Ukrainian officials said their forces had pushed armed militants out of three small eastern towns and were attacking more than 100 targets. But they said rebels were still attacking border checkpoints and army positions.

Military analysts said the Ukrainian troops will struggle to win decisively unless Russian President Vladimir Putin stems the flow of fighters and weapons across the border.

In Berlin, the foreign ministers of Ukraine, Russia, Germany and France pledged at a hastily arranged meeting to work toward a cease-fire "to be observed by all concerned."