Qatar's emir Tamim Bin Hamad Al Thani (Photo: Reuters)
It may be a meeting of allies, but when Qatar's emir holds talks with US President Barack Obama in Washington on Tuesday, there are several issues which could test that friendship.
The meeting will be the first official visit to the White House by Sheikh Tamim bin Hamad al-Thani, who has been Qatar's ruler since June 2013.
The meeting was announced cordially, with the White House saying in a statement last week that Obama was looking forward to discussing "political, economic, and security issues of mutual concern to our two countries".
But those security issues -- which are set to dominate the talks -- could also provide the greatest friction between the two leaders, analysts said.
"There is a very frank discussion that needs to be had," said Michael Stephens, head of the Royal United Services Institute for Defence and Security Studies (RUSI) Qatar.
Doha's fractious relationship with Egypt will be a major subject of discussions, Stephens said.
Last week Qatar recalled its envoy to Cairo following a row over Egypt's air strikes on Islamic State group targets in Libya.
Qatar expressed reservations over the strikes at a meeting in Cairo of the Arab League, raising the ire of Egypt's delegate Tareq Adel who hit back by accusing Doha of supporting "terrorism" in Libya.
The Gulf state responded by recalling its ambassador to Cairo for consultations.
The rift could complicate Washington's efforts to maintain a united front against IS and its affiliates across the region.
Qatar is a member of the US-led coalition carrying out air strikes against IS in Syria while Egypt is a longstanding US military ally.
"Obama will want to know how Qatar plans to manage its relationship with Egypt," Stephens said.
The US and Qatar are sometimes uneasy allies.
Qatar plays host to a large US military base, there is $7 billion worth of bilateral trade between the two countries and the United States has praised Doha for its role in trying to resolve unrest in Yemen, where militiamen have seized the capital.
But -- like Egypt's envoy at the Arab League -- some in the United States have accused Qatar of backing hardline Islamist groups in Libya, Egypt and elsewhere.
"There is opinion, particularly on the right of the spectrum (in the US) that Qatar is public enemy number one and Qatar hasn't done a particularly good job of defending itself," Stephens said.
In the days ahead of the emir's visit, some US rightwingers have asked why Obama will meet the head of a "jihadist-supporting country" but not Israeli Prime Minister Benjamin Netanyahu when he is to address Congress on March 3.
Qatar is accused of backing Palestinian militant group Hamas -- its chief, Khaled Meshaal, is based in the Gulf state -- and further suspicions were raised in the US last year during the release of American soldier Bowe Bergdahl.
He was held by the Taliban in Afghanistan but released in an exchange deal which saw five Taliban members freed to live in Qatar.
Qatar vigorously denies supporting IS.
Officials in Doha have said they are not funding radical groups but moderate ones and are doing so in coordination with the CIA and other Western intelligence agencies.
Christopher Davidson, an expert on Middle East politics at Durham University in Britain, said Qatar has been a loyal ally to the US since the beginning of the Arab Spring in 2011.
It backed groups that Washington also initially supported as regimes crumbled, but the radicalisation of some of those factions left Qatar being accused of supporting extremists, he said.
"I don't really buy this charge that Qatar is a shrewd operator," Davidson said. "Since the beginning of the Obama administration, Qatar has positioned itself as a useful second fiddle (for the US) in the Middle East."