The sudden, steep escalation of tensions between Saudi Arabia and Lebanon only got steeper Thursday, when the Saudi Ministry of Foreign Affairs advised the country's citizens to leave Lebanon. The advisory comes just days after Lebanese Prime Minister Saad Hariri announced his resignation in a televised address from Riyadh, the Saudi capital.

"Due to the situations in the Republic of Lebanon," read the bulletin in the state-run Saudi Press Agency, a source with the ministry "stated that the Saudi nationals visiting or residing in Lebanon are asked to leave the country as soon as possible.

"The Kingdom advised all citizens not to travel to Lebanon from any other international destinations," the bulletin added.

Saudi allies Kuwait and Bahrain have issued similar travel warnings of their own this week.

But the advisory carries particular significance in Saudi Arabia, where the Lebanese premier read his resignation announcement Saturday. Hariri, who has extensive ties to Saudi Arabia, shocked his country, party and even several of his closest advisers when he did so — and he hasn't set foot back inside Lebanon borders since. In fact, he's left Saudi Arabia just once, visiting the United Arab Emirates on Tuesday and immediately returning.

In Lebanon, Hariri's absence has inspired suspicion that he is being held against his will by the Saudis. Citing anonymous state sources, Reuters reports that the Lebanese government believes this, as well.

The Saudis have denied that Hariri is under house arrest.

For his part, Hariri said in his speech Saturday that he feared an assassination attempt, and that his decision to step down reflected fear for his life. His father, who also served as Lebanon's prime minister, was assassinated in 2005.

Still, Hariri's rationale hasn't stifled the churn of speculation back in Lebanon, where power is held by a coalition including Hariri's predominantly Sunni party called the Future Movement and Hezbollah, a Shiite group supported by Iran.

Hariri served as prime minister 2009 to 2011 and returned to office late last year. And though some in Lebanon have blamed Hezbollah for his father's assassination, Hariri has struck a moderate tone with regard to the group, telling NPR's Rachel Martin earlier this year that "this is something that I cannot take personal. There is an international tribunal that is working on the assassination of Rafik Hariri."

After his visit to the White House earlier this year, Hariri was asked about President Trump's remark that the militant group is a "menace." And Hariri would only go so far as to note "I think most administrations have said the same thing about Hezbollah."

Hariri's careful phrasing offers a window onto the political dynamic in the Persian Gulf region. As The Two-Way has noted previously, Saudi Arabia and Iran have been engaged in a tug-of-war over power in the region — and some believe the brash new Saudi crown prince, 32-year-old Mohammad bin Salman, might be dissatisfied by Hariri's lighter touch.

NPR's Greg Myre hasmore of the context behind the controversy:

"The Saudis have long supported Hariri, a fellow Sunni Muslim, and the Hariri family made its fortune from a construction business in the kingdom.

"The Saudis apparently felt Hariri was being undermined by Hezbollah, a Shiite group closely aligned with Iran. Yet many analysts are scratching their heads, wondering how Hariri's resignation will ultimately work to Saudi Arabia's advantage.

" 'One of the questions I have about all these Saudi actions is what is the end game and what is your strategy for getting to it,' said Alterman, citing Lebanon as one of several examples. 'It still may all work out. But the fact is, none of it has worked out yet and the Saudis seem to have doubled down on a strategy of embracing more risk.' "

Saudi Arabia, which has led airstrikes in Yemen and a blockade of Qatar, has sought to rally its allies in the region — including the UAE — to assert Sunni interests against those of Iran.

In Lebanon, Hariri's party issued a statement Thursday declaring that it was "necessary" for him to return in order "to restore Lebanon's dignity and respect," according to The Associated Press. And Lebanese Foreign Minister Gebran Bassil also posted a rather pointed subtweet of his own Thursday.

"We are the ones who chose our representatives," he said, "and we are the ones who decide to remove them."

For now, though, NPR's Ruth Sherlock notes that the Saudi advisory against visiting Lebanon is "terrible news for this country. It has long relied on Gulf tourism" — and though that tourism faded at the start of the Syrian civil war, it "was just picking up again."

Saudi Arabia has seen its own political upheaval of late.

Crown Prince Mohammad bin Salman has accelerated a campaign to quash rivals and consolidate power. Just hours after the prince was picked to lead a new anti-corruption commission — and just hours after Hariri announced his resignation — Saudi authorities launched a sweeping roundup in which 11 Saudi princes and other notables were arrested.

"A total of 208 individuals have been called in for questioning so far," Saudi Attorney General Sheikh Saud al-Mojeb said in a statement released Thursday by the Saudi Press Agency. He added that seven of those people have been released without charge.

"Based on our investigations over the past three years, we estimate that at least $100 billion USD has been misused through systematic corruption and embezzlement over several decades."

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