The White House published an executive order on Wednesday vowing to defend Qatar in the event of an attack from another country, a remarkable security guarantee for a single country akin to NATO’s Article V.

The order, which President Donald Trump signed Monday, states that the White House will now consider “any armed attack” on Qatar “as a threat to the peace and security of the United States.”

And, in the event of any attack, the U.S. would take “all lawful and appropriate measures — including diplomatic, economic and, if necessary, military — to defend the interests of the United States and the State of Qatar.”

Trump signed the executive order on the same day that he hosted Israeli Prime Minister Benjamin Netanyahu at the White House and orchestrated a phone call with the Qatari prime minister during which Israel’s leader apologized for missile strikes last month targeting Hamas officials while they were in Doha for ceasefire talks. The attack killed a Qatari security officer. The president, shortly after the attack, promised the Qataris it would not happen again.

The unilateral creation of any Article V-like security guarantees by a president — under the Constitution, treaties must be ratified by the Senate— is highly unusual, especially for a president who espouses an “America First” foreign policy and has questioned longstanding U.S. commitments to NATO and the central pillar of its charter that similarly deems an attack on any member country as an attack on the entire alliance.

That said, Trump’s order allows the president significant flexibility in determining how the U.S. would respond to an attack on Qatar.

Qatar was one of three Arab countries Trump traveled to in March during the first major foreign trip of his second term. Shortly after the trip, he accepted a $400 million 747 jetliner from the Qatari government as a gift and the Pentagon began efforts to refurbish and secure the plane so it can be used as a new Air Force One before the end of Trump’s term. Qatar also hosts the largest U.S. military installation in the Middle East.

The White House declined to comment on the order.

Jack Detsch contributed to this report.