Qatari Emir Sheikh Tamim bin Hamad Al Thani is meeting United States President Donald Trump in Washington, DC, to discuss regional security in the Persian Gulf and mutual economic ties, among other issues.
The emir's visit on Tuesday comes amid heightened tensions between Iran and the US and an ongoing blockade imposed on Qatar by its Arab neighbours.
The two leaders are scheduled to participate in an afternoon of meetings that will include a working lunch and the signing of a deal for Qatar to purchase Boeing jets.
Trump told reporters in the morning that Qatar is investing heavily in the US, buying military equipment and commercial planes.
Tuesday's meeting takes place a day after the emir held talks with acting US Defence Secretary Mark Esper at the Pentagon and attended a dinner banquet hosted by US Treasury Secretary Steven Mnuchin, where Trump was also present.
In a speech during the dinner, Qatar's emir said that his visit to the US reaffirmed the ideals the two countries shared and celebrated their mutual economic partnership.
"Our nations share a commitment to human capital, working to create resilient, knowledge-based economies with an emphasis on education, openness and opportunity for all," he said.
"Unfortunately, there are some in my region who do not share our beliefs. In today's world, at times, alliances have to be made with necessary partners, and certain allies are not actually friends," he also said, in an apparent reference to his country's Arab neighbours that are part of the blockade.
"But with the United States and Qatar, we are partners, allies and friends. We continue our mutual commitment to remain closely invested in both military and security alliance."
Saudi Arabia, the United Arab Emirates (UAE), Bahrain and Egypt have enforced a sea, air and land blockade against Qatar since June 2017.
The blockading countries have accused Doha of having strong ties with Iran, interfering in regional affairs and supporting "terrorism". Qatar has strongly denied these allegations.
Trump said at Monday's dinner that his friendship with the emir predated his own entry into politics.
"Tamim, you've been a friend of mine for a long time, before I did this presidential thing, and we feel very comfortable with each other," the US president said.
"Investments that you make in the United States - one of the largest in the world - are very much appreciated," Trump added.
Earlier this week, Qatar hosted talks between the Taliban and Afghan leaders in Doha.
The so-called intra-Afghan dialogue, sponsored by Qatar and Germany, between Afghan politicians, civil society members, including women, and the Taliban is seen as a substantive step towards peace in Afghanistan.