Qatar is sending its prime minister to Tehran in a fresh push to revive diplomacy, as Washington and Iran escalate a war of words over the United States’ vow to tighten economic pressure by sanctioning Tehran’s trading partners. Both sides at odds over control of Hormuz, chokepoint for global oil supplies that Tehran has used as leverage Key points and original sources are listed below.

• Qatar is sending its prime minister to Tehran in a fresh push to revive diplomacy, as Washington and Iran escalate a war of words over the United States’ vow to tighten economic pressure by sanctioning Tehran’s trading partners. Qatar, a Gulf neighbour of Iran...S1

• Both sides at odds over control of Hormuz, chokepoint for global oil supplies that Tehran has used as leverageS2