A PAC-3 Patriot missile unit in Japan. (Koji Sasahara/AP)

The United States plans to sell the United Arab Emirates $2 billion worth of Patriot missiles in an arms deal announced shortly before President Trump begins a tour of Middle Eastern nations.

The weapons include 60 Patriot Advanced Capability 3 (PAC-3) missiles and 100 Patriot Guidance Enhanced Missile-Tactical (GEM-T) missiles, along with supporting equipment and services from U.S. government personnel and contractors, the Defense Security Cooperation Agency (DSCA) said on its website. Congress was notified of the sale this week.

“The UAE will use the capability as a deterrent to regional threats and to strengthen its homeland defense,” DSCA said.

The UAE, one of the closest U.S. allies in the Middle East, has voiced alarm at what it sees as a rise in Iranian support for militant groups across the region, including in Yemen, where it is part of a Saudi-led coalition battling Shiite Houthi rebels.

Those concerns will form an important part of the discussion when Trump meets with leaders from Gulf nations, including the UAE, in Saudi Arabia during an inaugural overseas trip that begins next week.

Ilan Goldenberg, a former State Department and Pentagon official and a Middle East expert at the Center for a New American Security, said the UAE had been seeking to strengthen its missile defense abilities in recent years, and described the new sale as a “natural continuation” of an important defense relationship. The United Arab Emirates has used Patriot batteries since 2009, according to DSCA.

The country fields Patriot batteries in the UAE itself and also in Yemen, where they have been used to intercept missiles launched by Houthi forces.

“High-level meetings often help push these types of initiatives along,” Goldenberg said. “It is likely that [Mohammed bin Zayed al-Nahyan, the crown prince of Abu Dhabi’s] visit to the United States and meeting with President Trump, combined with Trump’s visit to the Gulf, helped generate a boost to get this done before the visit.”

Zayed is scheduled to hold talks with senior officials in Washington early next week.

Patriot missiles are some of the most world’s most sophisticated surface-to-air defense tools. The system, developed by Raytheon and Lockheed Martin, can intercept incoming missiles or aircraft as small as a commercial drone.

Defense Secretary Jim Mattis said this week that the United States may move a long-range Patriot battery to Lithuania amid increasing tension with Russia. It would the first of its kind to be stationed in the Baltics.