When Saudi Arabia's war in Yemen erupted in March 2015, there was widespread Saudi popular support for it - including by me.
Like other Saudi citizens, I was concerned about Iran's sectarian expansionist policies, as its influence has extended across the entire region north of the Saudi borders, the "Shi'ite crescent" that extends from Iran to the Mediterranean.
Today, Iran can easily construct a highway extending from Teheran to Beirut across Iraq, Syria and Lebanon. This arc of influence is a very real threat to Saudi Arabia.
Also, I strongly supported the war against Houthi rebels because I saw them as the antithesis of the Arab Spring that my government, unlike me, fiercely opposed.
The Houthis swept to power in the months before the Saudi-led campaign, refusing power-sharing arrangements that were supposed to transition Yemen into a democracy after three decades of dictatorship. By March 2015, the rebels had forced the legitimate Yemeni president and his government to flee the country.
Yet now, I am increasingly concerned that my country has failed to stem the Iranian advance despite the enormous spending on the war - there are credible estimates of US$200 million (S$270 million) a day - which has exhausted the Saudi budget.
Saudi Arabia has depleted one-third of its financial reserves, which have declined to around US$400 billion. US-made Patriot missile systems, at an average cost of US$3 million each, are in high demand to protect vital infrastructure, including Red Sea desalination plants.
More than the economic consequences, the political fallout for Saudi Arabia is much worse. Today, Yemen is teetering on the verge of a humanitarian disaster so vast that it is facing the world's most serious famine since the great drought hit Africa in the 1990s.
According to the World Food Programme, 17 million Yemenis (out of a total population of 28 million) will be affected.
Former Central Intelligence Agency senior adviser Bruce Riedel said recently at the Brookings Institution: "It started as Decisive Storm; the only thing that's 'decisive' today is that it's the worst humanitarian disaster in Yemen."
Saudi Arabia, more than any other country, is seen as responsible for the dire situation in Yemen. My country's reputation has been badly damaged and our credibility weakened.
Images of starving children should overwhelm even the most stalwart defender of the Saudi security interests that led us to destroy the poorest, most illiterate country in the Arab world.
Saudi Arabia announced it will lift the blockade on the port of Hodeida for United Nations humanitarian aid to come through. But ultimately, the only way out is to stop the war in Yemen. The UN has tried repeatedly and failed.
Only Saudi Arabia can initiate a complete reboot of peace talks. It did so in 1965 to end the Yemen civil war and can do so again today - by repositioning itself from an active participant in the war to a guarantor of peace.
Despite taking sides in the first Yemen civil war, King Faisal was able to withdraw and lead the peace negotiations, successfully ending the war. He invited all sides to his palace, where, at the Taif Conference, participants drew the road map to peace.
In the current conflict, Crown Prince and Defence Minister Mohammed bin Salman, popularly known as MBS, should see the past as precedent and similarly inspire peace by offering a grand gesture - it must curb funding and other support for the war.
The international community would need to pressure the Houthis - and Iran - to accede to a fair, negotiated settlement.
Saudi Arabia would recognise the Houthis as a legitimate Yemeni faction; the Houthis would have to similarly acknowledge other Yemeni factions.
All sides would agree to a power-sharing arrangement that guarantees Yemen's integrity as a unified nation. MBS would then achieve the upper hand by exposing Iran and the Houthis if they refuse to negotiate a comprehensive end to this horrific war.
MBS would gain the credibility needed to negotiate a ceasefire and then the terms of peace.
By facilitating a peace agreement and leading the reinvestment and reconstruction in Yemen, Saudi Arabia can turn around a failed state and bolster its standing as a global and regional leader.
However, to do any of this, as King Faisal did in 1965, MBS must end his campaign against political Islam and his clear intolerance for core democratic principles such as freedom of expression - both at home and in Yemen.
Earlier this month, MBS took a brave step by meeting the leaders of the Yemeni Islah Party, which is considered a branch of the Muslim Brotherhood, which is designated, rather unfairly and non-strategically, by Saudi Arabia as a terrorist organisation.
Saudi Arabia should feel safe with a representative government in Yemen that includes its allies and rivals. This was exactly what Saudi Arabia achieved in 1965, and it is capable of doing it again.
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