DUBAI, United Arab Emirates (AP) " By putting Iran "on notice," the new U.S. administration is laying the groundwork for a more confrontational approach toward the Islamic Republic.
What that means in practice is anyone's guess, since the White House isn't saying. That is in line with President Donald Trump's desire to keep America's adversaries guessing and boost U.S. leverage.
The U.S. has plenty in its toolbox should it choose to confront Iran more aggressively, from ratcheting up sanctions all the way to full-out war. Each carries real risks.
That's because Iran, however unpopular in Washington, is not a failed-state pushover. It is sure to respond if it feels it is under threat.
Here are some of the main issues:
WHY IS IRAN "ON NOTICE?"
In his surprise appearance in the White House briefing room, Trump's national security adviser, Michael Flynn, blasted Iran for threatening American allies and "malign actions " including weapons transfers, support for terrorism, and other violations of international norms."
He also linked Iran directly to missile attacks by Yemeni Shiite rebels known as Houthis on Saudi and Emirati ships. Saudi Arabia and the United Arab Emirates are leading a coalition supporting Yemen's internationally recognized government against the Iranian-backed rebels. Iran denies arming the rebels.
What appeared to trigger the notice being served, however, was Iran's Sunday launch of a medium-range ballistic missile. A U.N. Security Council resolution prohibits Iran from testing ballistic missiles specifically designed to carry a nuclear warhead.
The U.S. and Iran disagree on whether this and previous launches " including one in March 2016 involving a missile emblazoned with the phrase "Israel must be wiped out" in Hebrew " violate the ban.
WHAT HAPPENS NEXT?
Senior Trump administration officials have said they are considering options including economic measures and more support for Iran's regional rivals.
Among the biggest of those adversaries are Saudi Arabia, Israel and the UAE, whose foreign minister has voiced support for Trump's decision to temporarily block entry to citizens of Iran and six other Muslim-majority countries.
The Saudis and Emiratis would welcome deeper American involvement for the war in Yemen, which they view in large part as a proxy fight against Iran. The U.S. has provided logistical support to the Saudi-led coalition since it intervened in March 2015, but in December the Obama administration halted some arms sales to the Saudis over concerns about civilian deaths.
Washington could implement further unilateral sanctions against Iran. Nuclear-related sanctions were removed last year after Iran agreed to a deal with world powers limiting its nuclear activities, but Washington has maintained other sanctions related to support for terrorism and other actions as far back as the 1979 Islamic Revolution.
Torbjorn Soltvedt, a Middle East analyst at risk consulting firm Verisk Maplecroft, predicted that any new sanctions related to ballistic missile tests would target Iran's engineering industry.
"There is no doubt now that further flare-ups could translate into additional sanctions," he wrote.
WHAT IS THE VIEW FROM IRAN?
Iran is as distrustful of the United States as Washington is of Tehran, and the countries' views of one another often seem like distorted mirror images.
From Iran's perspective, the U.S. is a meddlesome outside power that has kept it surrounded for years with warships and troops in neighboring Afghanistan and Iraq.
Iran has not responded directly to Flynn's comments, although the Revolutionary Guard's acting commander was defiant that it would continue its missile development program.
"Iran's great missile power is one of the world's unmatched deterrent powers today," Gen. Hossein Salami was quoted as saying by the semi-official Tasnim news agency Thursday.
Iran's leaders are likely to see any new U.S. measures as a provocation in the wake of the nuclear deal.
The agreement was cheered by many in Iran because it lifted crippling economic sanctions and is opening up new business opportunities with the West, including a historic, $16.6 billion deal with Boeing to buy 80 U.S.-made jetliners.
IS A MILITARY CLASH POSSIBLE?
U.S. officials have not confirmed whether military action is on the table. It's unlikely to be the first step.
Maha Yahya, director of the Carnegie Middle East Center in Beirut, said a push for tougher sanctions or some form of diplomatic censure is more likely for now.
"It's far too early in the game for us to see any kind of military moves," she said.
Still, U.S. forces are already in place should Trump decide to launch at least a limited strike.
Guided-missile destroyers and other U.S. warships attached to the Navy's 5th Fleet routinely patrol the Persian Gulf and occasionally have unnervingly close encounters with Iranian Revolutionary Guard vessels. Just this week, 17 ships from the U.S., Australia, Britain and France took part in joint naval exercises in the Gulf.
At least one U.S. aircraft carrier is usually in the region, although not right now. The nearest one was last reported to be in the Western Pacific.
The U.S. does have warplanes capable of carrying out airstrikes stationed elsewhere in the region, including Qatar and the UAE. They have been actively targeting positions of the Islamic State group in Iraq and Syria.
HOW COULD IRAN RESPOND?
Iran is likely to calibrate its responses based on how the U.S. acts.
Tougher U.S. sanctions could convince Tehran to start reinterpreting the terms of the nuclear deal, said Mohammad Marandi, a political analyst in Tehran.
"The Iranians will reciprocate," he said. "The more the Americans disregard the agreement ... the more the Iranians will find new ways of interpreting the text that do not work to the benefit of the United States."
More direct action could include an uptick in harassment of U.S. warships by Revolutionary Guard speedboats in the Gulf, or new cyberattacks like one that crippled the network of Saudi Arabia's state oil company in 2012.
Iran also could boost support for regional allies such as Lebanon's Hezbollah or the Houthis in Yemen.
A military strike could elicit a much more damaging response.
Iranian officials have repeatedly vowed to shut the Strait of Hormuz at the mouth of the Gulf if Iran comes under threat. Doing so would stop the flow of a nearly a third of all oil traded by sea and likely draw the U.S. into a naval battle.
Iran could also target U.S. military bases or allied countries in the region with existing missiles, which it says can travel up to 2,000 kilometers (1,200 miles). Much of the Middle East, including Israel, falls within that range.
EDITOR'S NOTE: Adam Schreck, the Gulf news director for The Associated Press, has reported from across the Middle East since 2008.
Associated Press writers Amir Vahdat and Mahdi Fattahi in Tehran, Iran, and Andrea Rosa in Beirut contributed.
Follow Adam Schreck on Twitter at www.twitter.com/adamschreck
This story has been automatically published from the Associated Press wire which uses US spellings