The fight between two well-armed regional powers has their neighbors worried about the conflict spreading, a concern worsened by the prospect of U.S. involvement.

Understanding President Trump’s shifting position on an intensifying conflict.

The fight between two well-armed regional powers has their neighbors worried about the conflict spreading, a concern worsened by the prospect of U.S. involvement.

As Iran appears to be considering its options, its foreign minister was expected to meet with a key ally, President Vladimir V. Putin of Russia.