Ukrainians go on counteroffensive near capital even as Russia moves into strategic port

LVIV, Ukraine — Ukrainian forces defending the capital, Kyiv, managed to wrest back control of a strategic outlying town that Russian troops had earlier captured, Ukrainian officials said Tuesday, but invading troops were reported to have breached the besieged port city of Mariupol, scene of some of the war’s most harrowing attacks on civilians.

Russia’s massive but seemingly foundering invasion of its western neighbor lurched toward the beginning of a second month. Western officials redoubled warnings that an increasingly frustrated Russian President Vladimir Putin might resort to use of chemical or other unconventional weapons — a concern expected to dominate a NATO summit Thursday, with President Joe Biden in attendance.

In Russia, where Putin has recently imposed some of the most repressive measures of his more than two decades in power, the country’s premier