Ecuadoreans have voted against allowing the return of foreign military bases in the country, frustrating US hopes of expanding its presence in the Eastern Pacific region.
The referendum result is a blow to Ecuador's President Daniel Noboa, who had campaigned to change the constitution in order to reverse a ban that the country's legislature passed in 2008.
He said it would help fight organised crime and reduce the soaring violence the country has seen in recent years, during which it has become one of the world's biggest drug-trafficking hotspots.
The US had hoped the referendum would pave the way for it to open a military base, 16 years after it was made to close a site on the Pacific coast.
While Ecuador does not produce cocaine, its huge ports and proximity to Colombia and Peru - where large quantities of the drug are made - make it a desirable and lucrative location for drug-trafficking gangs.
According to Noboa, about 70% of the world's cocaine passes through Ecuador.
His presidency has been defined by a tough military crackdown on criminal gangs, including by putting armed soldiers on the streets. Supporters say his approach has helped to fight crime, but critics say his government has resorted to authoritarian tactics.
The US's former military base on Ecuador's Pacific coast was closed after left-wing president Rafael Correa decided not to renew its lease and pushed for a constitutional ban which was passed by lawmakers.
US Homeland Secretary Kristi Noem recently toured military facilities in Ecuador with Noboa.
In a BBC interview earlier this year, Noboa said he wanted foreign armies to join what he has described as a war against narco-trafficking groups. He has recently held talks over increased regional security and migration co-operation with US officials.
The referendum also saw voters reject ending public funding for political parties, shrinking the size of Congress, and establishing a constitutional assembly to re-write Ecuador's constitution.
Noboa had argued a fresh constitution could allow for tougher punishments for criminals and stronger measures to secure the borders, but critics argued it would not solve wider social problems like insecurity and poor access to education or healthcare in some areas.
Critics also feared the plans to reduce funding for political parties and the size of Congress could lead to a reduction in checks and balances on the government and representation in poorer areas, though the government hoped it would save public funds.
Noboa reacted by saying he would respect the outcome of the vote.
On the day of the referendum, the leader of one of Ecuador's biggest drug-trafficking gangs, Los Lobos, was captured in an operation involving Spanish police.
According to Noboa, Wilmer Pipo Chavarria had faked his own death and had been hiding in Europe while controlling criminal operations like drug-trafficking, ordering murders and illegal mining in Ecuador.
Both Ecuador and the US have designated Los Lobos as a terrorist organisation under domestic law.
This referendum played came as the US sent its largest military deployment to the Caribbean in decades, including the world's largest warship and bomber planes.
It has carried out at least 21 strikes on alleged drug-trafficking vessels in the Eastern Pacific and the Caribbean, killing at least 83 people. It has not provided evidence about who is on board and some lawyers have said the strikes could breach international law.
Speculation is mounting over whether the US will strike land targets in Venezuela. The US alleges that its President Nicolás Maduro is the head of a narco-trafficking organisation, an accusation he strongly denies.
Many observers believe the US military build-up in the region is also an attempt to put pressure on Maduro to force him from power.
