The United States is calling for a de-escalation of tensions between Saudi Arabia and Lebanon, following the resignation of Saad al-Hariri as Lebanon's prime minister while in Saudi Arabia.
On Thursday, Saudi Arabia asked its citizens in Lebanon to leave the country as soon as possible.
The U.S. State Department said it was "monitoring the situation very closely."
State Department spokesperson Heather Nauert said Thursday: "We would call for no kind of escalation of any sort of threats or something in that arena. But we also recognize that a government has the right to communicate with its own citizens."
Nauert confirmed in a briefing that a senior American diplomat at the U.S. Embassy in Riyadh — Chargé d'Affaires Christopher Henzel — met with Hariri on Wednesday.
The meeting was described as "sensitive, private, diplomatic conversations," yet no details were provided on whether Hariri was being held.
Saudi Arabia supported Hariri, who is currently under house arrest, and his allies during years of political conflict in Lebanon with Iran-backed Hezbollah.
Hariri's resignation was widely seen as imposed by his backers in the Saudi Arabian monarchy in reaction to the growing influence of Shiite Iran and its Lebanese proxy, Hezbollah, in the region. Riyadh denied claims that it had forced Hariri to resign.
A Lebanese matter
The State Department said Hariri's decision to resign was an internal matter and that Washington did not anticipate its relationship with the Lebanese government would change as a result.
On Tuesday, U.S. Secretary of State Rex Tillerson spoke with Saudi Foreign Minister Adel al-Jubeir about the Hariri situation.
"The issue was brought up," Nauert said, adding, "These are all very sensitive matters."
A Saudi Foreign Ministry source quoted Thursday by the kingdom's official news agency said, "Due to the circumstances in the Lebanese Republic, the kingdom asks its citizens who are visiting or residing" there to leave as soon as possible.
Riyadh has also discouraged its citizens from traveling to the neighboring country in the wake of Hariri's announcement of his resignation Saturday.
In late July, Tillerson welcomed Hariri at the State Department in Washington, where "Syria and regional security issues" were discussed.
Other countries in the region, including Kuwait, also called on their citizens to leave Lebanon.
The U.S. last issued a travel warning on Lebanon on February 15 "because of the threats of terrorism, armed clashes, kidnapping and outbreaks of violence, especially near Lebanon's borders with Syria and Israel. "
It was unclear whether the U.S. planned to renew its travel warning on Lebanon.