The rise to power in Thailand of a 37-year-old heiress portends new hope for reviving Thai-American relations after years in disrepair.

Paetongtarn Shinawatra appears so pleased to have been elected prime minister by the parliament, virtually unopposed, that she’s confining herself to happy talk that speaks volumes about the relief of emerging unscathed from yet another Thai political crisis.

Ms. Shinawatra will, no doubt, get to foreign policy, including Thai-American relations. There’s no telling how long this daughter of the once popular prime minister, Thaksin Shinawatra, and niece of his sister, Yingluck, also a former prime minister, will stay in office, but for now she’s simply saying, “We are determined, together, and we will push the country forward.”

She didn’t have to hark back to the downfall of both her father and aunt, each overthrown in military coups supported by the country’s highest court, each forced into years in exile, each more or less rehabilitated in a country that’s known as “the land of smiles.” Nor did she mention her predecessor, Srettha Thavisin, ousted by court order on a dubious corruption charge.

Ms. Shinawata was all smiles as she talked to the press after 319 of the 489 members of the lower house of parliament voted for her. That is far more than the simple majority she needed. That done, she’s marking Thailand’s economic problems as her immediate concern, declaring, “I have confidence in all government coalition parties to bring our country out of the economic crisis.”

With the advice of her father, she’s expected quite soon to turn to concerns about Thai-American ties, which some suggest fall short of a full-fledged, viable alliance; Thailand next week is engaging in air force war games with Communist China. Experienced analysts nonetheless believe there’s reason for optimism, considering the long history of the relationship.

“The United States should accept that Thailand is not currently strategically aligned with Washington nor a full-fledged democracy,” a former American ambassador to neighboring Myanmar, Scot Marciel, writes in the Journal of Indo-Pacific Affairs. “Thailand can still play a crucial role as an important partner. This recognition, among other factors, necessitates patience concerning Thailand’s domestic politics and faith that the kingdom will not fall excessively under China’s influence.”

Mr. Marciel wrote those words while Mr. Srettha was prime minister, but they apply more than ever while Washington faces rising concerns about China’s influence not only in Thailand but in the entire region.

Ms. Shinawata is sure to turn to her father, who clung to the post of prime minister for five years before succumbing to a military coup and fleeing into exile in Dubai. Now, 15 years later, he’s not only back but cleared of the charges that would have put him in prison. She’s promised to carve out her own independent policy, but has to count on both her father’s popularity and his wealth, which Forbes estimates at $2.1 billion.

Her father’s legacy, and that of his sister, who was in office for nearly three years before being driven out by a coup, may serve Washington well in the quest for improved relations with Thailand. Upset by the failure of democracy, Washington cut back on military aid while the Chinese exploited the rift.

Now, America’s relations with Thailand may be at a turning point. 

“The Biden administration’s hesitant approach to the government in Thailand makes it abundantly clear that the U.S.-Thailand alliance is punching below its weight,” an analyst at the Center for Strategic and International Studies, Andreyka Natalegawa, wrote before the latest upheaval in Bangkok. 

While America’s Asian alliances “have flourished in recent years, the U.S.-Thailand alliance has largely languished,” he wrote, contrasting “this state of inertia” with “revitalization” of Washington’s “only other security alliance in Southeast Asia: the Philippines.”