The Israeli military said it killed Sinwar in southern Gaza on Wednesday and Hamas subsequently confirmed his death.

The standoff comes as Israel’s war with Lebanon’s Hezbollah, a Hamas ally backed by Iran, has intensified in recent weeks.

The stands taken by the two sides signal, at least publicly, that they have not moved any closer to ending their conflict.

The death of Hamas leader Yahya Sinwar has left the group without a commander. Could his younger brother, who is now believed ...