May 5: John Bolton, the White House national security adviser and a longtime Iran hawk, announces the deployment of the USS Abraham Lincoln carrier strike group and a bomber task force in response to "a number of troubling and escalatory indications and warnings," without providing details. He threatens "unrelenting force" in response to any attack.

May 8: Iran vows to enrich its uranium stockpile closer to weapons-grade levels starting July 7 if world powers fail to negotiate new terms for its nuclear deal. The US responds by imposing sanctions on Iran's metals industry.

May 9: The European Union urges Iran to respect the nuclear deal and says it plans to continue trading with the country despite US sanctions. Trump says he would like Iran's leaders to "call me."

May 10: The US says it will move a Patriot missile battery into the Middle East to counter threats from Iran.

May 12: The United Arab Emirates says four commercial ships off its eastern coast "were subjected to sabotage operations," just hours after Iranian and Lebanese media outlets air false reports of explosions at a nearby Emirati port.

May 13: European foreign ministers urge the United States and Iran to show restraint, while Secretary of State Mike Pompeo briefs his counterparts on the alleged threats from Iran. Trump warns that if Tehran does "anything" in the form of an attack "they will suffer greatly."

May 14: Yemen's Iran-aligned Houthi rebels launch a drone attack on Saudi Arabia, striking a major oil pipeline and taking it out of service.

The New York Times reports the White House is reviewing military plans that could result in sending 120,000 US troops to the Middle East if Iran attacks American forces or steps up work on nuclear weapons. Trump says it's "fake news," but that he would "absolutely" be willing to send troops if necessary.

Iran's Supreme Leader Ayatollah Ali Khamenei says "no one is seeking war," but that it wouldn't be difficult for Iran to enrich uranium to weapons-grade levels.

A senior military officer in the US-backed coalition fighting the Islamic State group says "there's been no increased threat from Iranian-backed forces in Iraq and Syria." In a rare public rebuttal, US Central Command says his remarks "run counter to the identified credible threats."

May 15: The US Embassy in Baghdad orders all nonessential government staff to leave Iraq immediately. The Netherlands and Germany say they are suspending their training of Iraqi forces.

May 16: Saudi Arabia blames Iran for the drone attack on its pipeline and an English-language newspaper close to the palace calls for the US to launch "surgical" strikes in retaliation.

President Donald Trump says he hopes the US is not on a path to war with Iran amid fears that his two most hawkish advisers could be angling for a conflict with the Islamic Republic. Asked if the US was going to war with Iran, the president replied, "I hope not" - a day after he repeated a desire for dialogue, tweeting, "I'm sure that Iran will want to talk soon."

May 19: A rocket lands near the US Embassy in Baghdad, without harming anyone. It's not clear who is behind the attack, but after the initial reports, Trump tweets: "If Iran wants to fight, that will be the official end of Iran. Never threaten the United States again!" Iran's foreign minister responded by tweeting that Trump had been "goaded" into "genocidal taunts."

May 20: Semi-official media in Iran report that it has quadrupled its production of low-enriched uranium, which is used for civilian applications but not nuclear weapons. Iran is allowed to enrich uranium to the low level of 3.67%, but increased production could lead it to exceed the stockpile limits in the nuclear deal.

May 24: President Donald Trump says the US will bolster its military presence in the Middle East with an additional 1,500 troops. He says the troops will have a "mostly protective" role.

- Senior Pentagon officer Vice Admiral Michael Gilday says the U.S. has a high degree of confidence that Iran's Revolutionary Guard was responsible for the explosions of the four tankers in the Gulf of Oman, and that Iranian proxies in Iraq fired rockets into Baghdad.

May 31 and June 1: Saudi Arabia's King Salman hosts three high-level summits in Mecca, drawing heads of state from across the Middle East and Muslim countries to present a unified Muslim and Arab position on Iran. The monarch calls on the international community to use all means to confront Iran and accuses the Shiite power of being behind "terrorist operations" that targeted Saudi oil interests.

June 12: Saudi Arabia says 26 people were wounded in an attack by Yemen's Houthi rebels targeting an airport in kingdom's southwestern town of Abha. The Houthis claim they'd launched a cruise missile at the airport.

June 13: Two oil tankers near the strategic Strait of Hormuz were reportedly attacked in an assault that left one ablaze and adrift as 44 sailors were evacuated from both vessels and the US Navy rushed to assist.