CHORNOMORSKOYE, Ukraine — Russian forces raided a Ukrainian naval missile base here in the darkness of early Monday, scaling its outer walls and outmatching the surprised sailors inside without firing a shot, according to the Ukrainian Ministry of Defense and people familiar with the raid.

The seizure was one of a series of swift but thus far bloodless escalations as Russia tightened its grip on Crimea, the Black Sea peninsula that the Kremlin is leading toward secession from Ukraine by a combination of military and political moves.

Russian forces also infiltrated an air base at Novofedorivka and took up position along a runway; took over a military hospital in the regional capital, Simferopol; and moved onto a Ukrainian base used by a motorized battalion in Bakhchysaray.

Russian soldiers penetrated the last base after firing in the air, said Vladislav Seleznev, a Ukrainian military spokesman in Crimea. No one was reported hurt.