Ukraine's easterly Donetsk region, dominated by Russian-speakers and buffeted by rallies by pro-Russian activists, has built a defensive trench complete with concrete barriers along its long border with Russia, its governor said Monday.

Sergei Taruta also said measures will be taken to restore order in the region in the aftermath of Russia's takeover of Crimea after pro-Russian demonstrators overwhelmed police and stormed public buildings.

Russian President Vladimir Putin says he reserves the right, after the takeover of Crimea, to protect eastern Ukraine's Russian-speaking majority from what Moscow says are right-wing allies of the pro-Western government in Kiev. Ukraine's defense minister says 60,000 Russian troops are massed on the border.

Taruta, appointed by the central government like all regional governors, said the aim of the trench project is to protect the 150 km (90 miles) of Donetsk region's border with Russia, particularly between established crossing points.

The trench, he said, is 4 meters (12 feet) wide, 2.5 meters deep and backed up by a dike 2 meters high.

"We have done this on our own and dug a trench practically the entire length of the border. In particularly dangerous places, concrete blocks standing on four legs have been put in place," Taruta told a news conference.

"Our border is not a castle. But it is equipped so that vehicles cannot cross it in either direction. This is not based on one or another scenario, but rather intended to maintain a solid border."