WASHINGTON — South Africa’s leader on Friday agreed to cooperate closely with US President Joe Biden on health, security and climate but warned against punishing African nations for maintaining ties with Russia. The Biden administration has put a new focus on Africa after being taken aback by the reluctance of some nations to condemn Russia over its invasion of Ukraine, which has triggered sweeping Western sanctions. President Cyril Ramaphosa enjoyed unusually warm treatment from Biden, who walked him back to his motorcade at the White House, weeks after Secretary of State Antony Blinken traveled to South Africa and promised that...