Britain's Prince William (L), Duke of Cambridge, attends a reception celebrating United Kingdom and Bhutanese friendship and cooperation in Thimphu, Bhutan, April 15, 2016. REUTERS/Mark Large/Pool 

Catherine, Duchess of Cambridge, attends a reception celebrating United Kingdom and Bhutanese friendship and cooperation in Thimphu, Bhutan, April 15, 2016. REUTERS/Mark Large/Pool 

Britain's Prince William (C), Duke of Cambridge and his wife Catherine (L), Duchess of Cambridge, attend a reception celebrating United Kingdom and Bhutanese friendship and cooperation in Thimphu, Bhutan, April 15, 2016. REUTERS/Mark Large/Pool 

Catherine (2nd R), Duchess of Cambridge, attends a reception celebrating United Kingdom and Bhutanese friendship and cooperation in Thimphu, Bhutan, April 15, 2016. REUTERS/Mark Large/Pool 

Britain's Prince William (L), Duke of Cambridge, attends a reception celebrating United Kingdom and Bhutanese friendship and cooperation in Thimphu, Bhutan, April 15, 2016. REUTERS/Mark Large/Pool 

Britain's Prince William (L), Duke of Cambridge, attends a reception celebrating United Kingdom and Bhutanese friendship and cooperation in Thimphu, Bhutan, April 15, 2016. REUTERS/Mark Large/Pool 

Catherine, Duchess of Cambridge, attends a reception celebrating United Kingdom and Bhutanese friendship and cooperation in Thimphu, Bhutan, April 15, 2016. REUTERS/Mark Large/Pool 

Britain's Prince William, Duke of Cambridge and his wife Catherine, Duchess of Cambridge, trek up the mountain to the Paro Taktsang Monastery, Bhutan, April 15, 2016. REUTERS/Cathal McNaughton TPX IMAGES OF THE DAY

Britain's Catherine, Duchess of Cambridge looks around the Tashichho Dzong temple in Thimphu, Bhutan April 14, 2016. REUTERS/Cathal McNaughton 

Britain's Catherine, Duchess of Cambridge looks around the Tashichho Dzong temple in Thimphu, Bhutan April 14, 2016. REUTERS/Cathal McNaughton 

Monks walk across a courtyard in the Tashichho Dzong temple in Thimphu, Bhutan April 14, 2016. REUTERS/Cathal McNaughton 

Britain's Prince William, Duke of Cambridge and his wife Catherine, Duchess of Cambridge are shown around the Tashichho Dzong temple by King Jigme Khesar Namgyel Wangchuck and his wife Jetsun Pema in Thimphu, Bhutan, April 14, 2016. REUTERS/Cathal McNaughton 

Monks bow to show respect as Britain's Prince William, Duke of Cambridge and his wife Catherine, Duchess of Cambridge are shown around the Tashichho Dzong temple by King Jigme Khesar Namgyel Wangchuck and his wife Jetsun Pema in Thimphu, Bhutan, April 14, 2016. REUTERS/Cathal McNaughton 

Britain's Catherine, Duchess of Cambridge is shown around the Tashichho Dzong temple by Queen Jetsun Pema Wangchuck in Thimphu Bhutan April 14, 2016. REUTERS/Cathal McNaughton 

Britain's Catherine, Duchess of Cambridge is shown around the Tashichho Dzong temple by Queen Jetsun Pema Wangchuck in Thimphu, Bhutan, April 14, 2016. REUTERS/Cathal McNaughton 

Britain's Catherine, Duchess of Cambridge is shown around the Tashichho Dzong temple by Queen Jetsun Pema Wangchuck in Thimphu, Bhutan, April 14, 2016. REUTERS/Cathal McNaughton 

Britain's Catherine, Duchess of Cambridge looks around the Tashichho Dzong temple in Thimphu, Bhutan, April 14, 2016. REUTERS/Cathal McNaughton 

Britain's Prince William, Duke of Cambridge and his wife Catherine, Duchess of Cambridge are shown around the Tashichho Dzong temple by King Jigme Khesar Namgyel Wangchuck and his wife Jetsun Pema in Thimphu, Bhutan, April 14, 2016. REUTERS/Cathal McNaughton TPX IMAGES OF THE DAY 

Britain's Prince William, Duke of Cambridge and his wife Catherine, Duchess of Cambridge are shown around the Tashichho Dzong temple by King Jigme Khesar Namgyel Wangchuck and his wife Jetsun Pema in Thimphu, Bhutan, April 14, 2016. REUTERS/Cathal McNaughton 

Britain's Catherine, Duchess of Cambridge arrives at the Tashichho Dzong temple in Thimphu, Bhutan, April 14, 2016. REUTERS/Cathal McNaughton 

Britain's Prince William, Duke of Cambridge prepares to shoot an arrow as Catherine, Duchess of Cambridge, looks on at Changlimithang Archery Ground in Thimphu, Bhutan, April 14, 2016. REUTERS/Cathal McNaughton 

Britain's Prince William, Duke of Cambridge prepares to shoot an arrow as Catherine, Duchess of Cambridge looks on at Changlimithang Archery Ground in Thimphu, Bhutan, April 14, 2016. REUTERS/Cathal McNaughton 

Britain's Catherine, Duchess of Cambridge reacts after shooting an arrow at Changlimithang Archery Ground, in Thimphu, Bhutan, April 14, 2016. REUTERS/Cathal McNaughton 

Britain's Catherine, Duchess of Cambridge reacts after shooting an arrow at Changlimithang Archery Ground in Thimphu, Bhutan, April 14, 2016. REUTERS/Cathal McNaughton 

Britain's Prince William, Duke of Cambridge throws a dart while taking part in the traditional game of Khuru at Changlimithang Archery Ground in Thimphu, Bhutan, April 14, 2016. REUTERS/Cathal McNaughton 

Britain's Catherine, Duchess of Cambridge throws a dart while taking part in the traditional game of Khuru at Changlimithang Archery Ground in Thimphu, Bhutan, April 14, 2016. REUTERS/Cathal McNaughton 

Britain's Catherine, Duchess of Cambridge reacts after throwing a dart while taking part in the traditional game of Khuru at Changlimithang Archery Ground in Thimphu, Bhutan, April 14, 2016. REUTERS/Cathal McNaughton 

Britain's Catherine, Duchess of Cambridge reacts after shooting an arrow at Changlimithang Archery Ground in Thimphu, Bhutan, April 14, 2016. REUTERS/Cathal McNaughton TPX IMAGES OF THE DAY 

Women carry flags in Tashichho Dzong, the seat of the head of Bhutan's Civil Government in Thimphu in preparation for the visit of Britain's Prince William and his wife Catherine, the Duchess of Cambridge, Bhutan, April 13, 2016. REUTERS/Cathal McNaughton 

A monk paints in Tashichho Dzong, the seat of the head of Bhutan's Civil Government in Thimphu, in preparation for the visit of Britain's Prince William and his wife Catherine, the Duchess of Cambridge, Bhutan April 13, 2016. REUTERS/Cathal McNaughton 

Young monks erect a marquee in preparation for the visit of Britain's Prince William and his wife Catherine, the Duchess of Cambridge, to Changangkha Lhakhang temple in Thimphu, Bhutan, April 13, 2016 REUTERS/Cathal McNaughton 

Young monks erect a marquee in preparation for the visit of Britain's Prince William and his wife Catherine, the Duchess of Cambridge, to Changangkha Lhakhang temple in Thimphu, Bhutan, April 13, 2016 REUTERS/Cathal McNaughton 

Bhutan's King Jigme Khesar Namgyel Wangchuck gestures as Queen Jetsun Pema watches during the king's ceremonial reception at the forecourt of India's presidential palace Rashtrapati Bhavan in New Delhi January 25, 2013. Bhutan's royal couple is on a week-long state visit to India and will be the chief guests at India's Republic Day celebrations on Saturday. REUTERS/Adnan Abidi (INDIA - Tags: POLITICS ROYALS TPX IMAGES OF THE DAY ENTERTAINMENT) 

Bhutan's King Jigme Khesar Namgyel Wangchuck (L) and Queen Jetsun Pema look on as they wait to meet Japan's Prime Minister Yoshihiko Noda at the Akasaka guesthouse in Tokyo November 15, 2011. Bhutan's royal couple are now in Tokyo on their six-day state visit to Japan. REUTERS/Yoshikazu Tsuno/Pool (JAPAN - Tags: POLITICS ROYALS) 

King Jigme Khesar Namgyel Wangchuck (L) kisses Queen Jetsun Pema in front of thousands of residents gathered for the third day of their wedding ceremony at the Changlimithang stadium in Bhutan's capital Thimphu on October 15, 2011. Bhutan's "Dragon King" married a young commoner in an ancient Himalayan monastic fortress on Thursday, sipping a chalice of ambrosia symbolizing eternal life in a Buddhist wedding that has transfixed a reclusive kingdom slowly embracing globalization. REUTERS/Adrees Latif (BHUTAN - Tags: ROYALS ENTERTAINMENT) 

A boy wearing the gho, the traditional and national dress for men in Bhutan, holds flowers while waiting at a roadside to see King Jigme Khesar Namgyel Wangchuck and Queen Jetsun Pema in Bhutan's capital Thimphu October 14, 2011. Bhutan's "Dragon King" married a young commoner in an ancient Himalayan monastic fortress on Thursday, sipping a chalice of ambrosia symbolizing eternal life in a Buddhist wedding that has transfixed a reclusive kingdom slowly embracing globalization. REUTERS/Adrees Latif (BHUTAN - Tags: ROYALS ENTERTAINMENT) 

King Jigme Khesar Namgyel Wangchuck and Queen Jetsun Pema greet villagers after their wedding in Bhutan's ancient capital Punakha October 13, 2011. Bhutan's "Dragon King" married a commoner in a Himalayan monastic fortress on Thursday, sipping a chalice of ambrosia symbolizing eternal life, in a wedding that has transfixed a reclusive kingdom slowly embracing globalization. REUTERS/Adrees Latif (BHUTAN - Tags: ROYALS) 

King Jigme Khesar Namgyel Wangchuck and Queen Jetsun Pema pose for pictures after their marriage at the Punkaha Dzong in Bhutan's ancient capital Punakha October 13, 2011. REUTERS/Adrees Latif (BHUTAN - Tags: ROYALS ENTERTAINMENT) 

A man decorates a portrait of King Jigme Khesar Namgyel Wangchuck and his fiancee Jetsun Pema after hanging it outside his shop in Bhutan's capital Thimphu on October 12, 2011. The Bhutanese king is scheduled to wed his fiancee Jetsun Pema over a three-day ceremony starting in the ancient capital Punakha on October 13. REUTERS/Adrees Latif (BHUTAN - Tags: ROYALS ENTERTAINMENT) 

Men carry a portrait of King Jigme Khesar Namgyel Wangchuck and his fiancee Jetsun Pema to display inside an office building in Bhutan's capital Thimphu on October 12, 2011. The Bhutanese king is scheduled to wed his fiancee Jetsun Pema over a three-day ceremony starting in the ancient capital Punakha on October 13. REUTERS/Adrees Latif (BHUTAN - Tags: ROYALS ENTERTAINMENT) 

Men carry a portrait of King Jigme Khesar Namgyel Wangchuck and his fiancee Jetsun Pema while searching for a location to display the image in an office building in Bhutan's capital Thimphu on October 12, 2011. The Bhutanese king is scheduled to wed his fiancee Jetsun Pema over a three-day ceremony starting in the ancient capital Punakha on October 13. REUTERS/Adrees Latif (BHUTAN - Tags: ROYALS ENTERTAINMENT) 

A woman signs to a neighbor next to a portrait of King Jigme Khesar Namgyel Wangchuck and his fiancee Jetsun Pema hanging outside her residence in Bhutan's capital Thimphu on October 12, 2011. The Bhutanese king is scheduled to wed his fiancee Jetsun Pema over a three-day ceremony starting in the ancient capital Punakha on October 13. REUTERS/Adrees Latif (BHUTAN - Tags: ROYALS ENTERTAINMENT) 

A man hangs a portrait of King Jigme Khesar Namgyel Wangchuck and his fiancee Jetsun Pema outside a building in Bhutan's capital Thimphu on October 12, 2011. The Bhutanese king is scheduled to wed his fiancee Jetsun Pema over a three-day ceremony starting in the ancient capital Punakha on October 13. REUTERS/Adrees Latif (BHUTAN - Tags: ROYALS ENTERTAINMENT) 

Men hang a portrait of King Jigme Khesar Namgyel Wangchuck and his fiancee Jetsun Pema on an archway in Bhutan's capital Thimphu on October 12, 2011. The Bhutanese king is scheduled to wed his fiancee Jetsun Pema over a three-day ceremony starting in the ancient capital Punakha on October 13. REUTERS/Adrees Latif (BHUTAN - Tags: ROYALS ENTERTAINMENT) 

Men hang a portrait of King Jigme Khesar Namgyel Wangchuck and his fiancee Jetsun Pema on an archway in Bhutan's capital Thimphu on October 12, 2011. The Bhutanese king is scheduled to wed his fiancee Jetsun Pema over a three-day ceremony starting in the ancient capital Punakha on October 13. REUTERS/Adrees Latif (BHUTAN - Tags: ROYALS ENTERTAINMENT) 

Men carry a portrait of King Jigme Khesar Namgyel Wangchuck and his fiancee Jetsun Pema before hanging it along a road in Bhutan's capital Thimphu on October 12, 2011. The Bhutanese king is scheduled to wed his fiancee Jetsun Pema over a three-day ceremony starting in the ancient capital Punakha on October 13. REUTERS/Adrees Latif (BHUTAN - Tags: ROYALS ENTERTAINMENT TPX IMAGES OF THE DAY) 

Men hang a portrait of King Jigme Khesar Namgyel Wangchuck and his fiancee Jetsun Pema on an archway in Bhutan's capital Thimphu October 12, 2011. The Bhutanese king is scheduled to wed his fiancee Jetsun Pema over a three-day ceremony starting in the ancient capital Punakha on October 13. REUTERS/Adrees Latif (BHUTAN - Tags: ROYALS ENTERTAINMENT TPX IMAGES OF THE DAY) 

A portrait of Bhutan's King Jigme Khesar Namgyel Wangchuck and his fiancee Jetsun Pema is seen pictured in a roundabout in the capital Thimphu October 11, 2011. The Bhutanese king is scheduled to wed his fiancee Jetsun Pema over a three-day ceremony starting in the ancient capital Punakha on October 13. REUTERS/Adrees Latif (BHUTAN - Tags: ROYALS ENTERTAINMENT) 

A school girl shows off a pin, with the images of King Jigme Khesar Namgyel Wangchuck and his fiancee Jetsun Pema, while taking part in a rehearsal ceremony ahead of the royal wedding in Bhutan's capital Thimphu on October 11, 2011. The Bhutanese king is scheduled to wed his fiancee Jetsun Pema over a three-day ceremony starting in the ancient capital Punakha on October 13. REUTERS/Adrees Latif (BHUTAN - Tags: ROYALS) 

A Bhutanese man adjusts his mask before taking part in a rehearsal ceremony ahead of the royal wedding of King Jigme Khesar Namgyel Wangchuck in Bhutan's capital Thimphu on October 11, 2011. The Bhutanese king is scheduled to wed his fiancee Jetsun Pema over a three-day ceremony starting in the ancient capital Punakha on October 13. REUTERS/Adrees Latif (BHUTAN - Tags: ROYALS SOCIETY) 

A Bhutanese man adjusts his mask before taking part in a rehearsal ceremony ahead of the royal wedding of King Jigme Khesar Namgyel Wangchuck in Bhutan's capital Thimphu on October 11, 2011. The Bhutanese king is scheduled to wed his fiancee Jetsun Pema over a three-day ceremony starting in the ancient capital Punakha on October 13. REUTERS/Adrees Latif (BHUTAN - Tags: ROYALS SOCIETY) 

Bhutanese men in traditional costumes take part in a rehearsal ceremony at the Changlimithang Stadium, ahead of the royal wedding of King Jigme Khesar Namgyel Wangchuck in Bhutan's capital Thimphu on October 11, 2011. The Bhutanese king is scheduled to wed his fiancee Jetsun Pema over a three-day ceremony starting in the ancient capital Punakha on October 13. REUTERS/Adrees Latif (BHUTAN - Tags: ROYALS SOCIETY) 

Bhutanese women wearing traditional costumes parepare to take part in a rehearsal ceremony ahead of the royal wedding of King Jigme Khesar Namgyel Wangchuck in Bhutan's capital Thimphu on October 11, 2011. The Bhutanese king is scheduled to wed his fiancee Jetsun Pema over a three-day ceremony starting in the ancient capital Punakha on October 13. REUTERS/Adrees Latif (BHUTAN - Tags: ROYALS SOCIETY) 

Bhutanese men don traditional masks while taking part in a rehearsal ceremony ahead of the royal wedding of King Jigme Khesar Namgyel Wangchuck in Bhutan's capital Thimphu on October 11, 2011. The Bhutanese king is scheduled to wed his fiancee Jetsun Pema over a three-day ceremony starting in the ancient capital Punakha on October 13. REUTERS/Adrees Latif (BHUTAN - Tags: ROYALS SOCIETY) 

Bhutanese men don traditional masks while taking part in a rehearsal ceremony ahead of the royal wedding of King Jigme Khesar Namgyel Wangchuck in Bhutan's capital Thimphu on October 11, 2011. The Bhutanese king is scheduled to wed his fiancee Jetsun Pema over a three-day ceremony starting in the ancient capital Punakha on October 13. REUTERS/Adrees Latif (BHUTAN - Tags: ROYALS SOCIETY) 

Bhutan's King Jigme Khesar Namgyel Wangchuck (L) walks beside his father, Bhutan's fourth King Jigme Singye Wangchuck, during coronation celebrations at Chang Lime Thang stadium in Thimphu November 8, 2008. Bhutan's new "People's King", as he has inevitably been nicknamed, is a young man who has also been educated in the United States and India and now wants to help shepherd his ancient Himalayan kingdom into the modern world. REUTERS/Desmond Boylan (BHUTAN) 

Bhutan's King Jigme Khesar Namgyel Wangchuck (C, in yellow) watches traditional games while sitting with the crowd at Chang Lime Thang stadium during coronation celebrations in Thimphu November 8, 2008. Bhutan's new "People's King", as he has inevitably been nicknamed, is a young man who has also been educated in the United States and India and now wants to help shepherd his ancient Himalayan kingdom into the modern world. REUTERS/Desmond Boylan (BHUTAN) 

Men play a traditional game at Chang Lime Thang stadium during coronation celebrations for Bhutan's King Jigme Khesar Namgyel Wangchuck in Thimphu November 8, 2008. Bhutan's new "People's King", as he has inevitably been nicknamed, is a young man who has also been educated in the United States and India and now wants to help shepherd his ancient Himalayan kingdom into the modern world. REUTERS/Desmond Boylan (BHUTAN) 

Bhutan's King Jigme Khesar Namgyel Wangchuck aims the arrow during coronation celebrations at Chang Lime Thang stadium in Thimphu November 8, 2008. Bhutan's new "People's King", as he has inevitably been nicknamed, is a young man who has also been educated in the United States and India and now wants to help shepherd his ancient Himalayan kingdom into the modern world. REUTERS/Desmond Boylan (BHUTAN)