BANGKOK, Thailand -- The U.S.-trained military's coup-installed government has begun its fifth year in power confronting pro-election activists in the streets, a troubled economy, and widespread cynicism over plans to dominate this Buddhist-majority country after polls next February.

Fifteen protest leaders, who demand elections this year, were charged with sedition and other serious crimes on May 24 after leading hundreds of activists who were stopped while trying to march to the prime minister's office on May 22.

"We have tried everything, but in the end, we might not be able to bring change and a return to democracy," said Rangsiman Rome, one of the arrested leaders who reluctantly called off their "People Who Want Elections" march after hours of confrontation in the street.

Some had mocked Prime Minister Prayuth Chan-ocha -- who led the May 22, 2014 coup when he was army chief -- by wearing face masks portraying him as a long-nosed Pinocchio.

They demand national elections this year, an immediate end to the junta's control, and the military to stop supporting the regime.

They are weary of Mr. Prayuth postponing the election date every year and suspect he will delay his latest promise for elections in February 2019.

After using military trials against civilian dissidents, "attitude adjustment" re-education camps, restrictions against political meetings of more than four people and other politicized laws, the junta denied abusing human rights because violators were imprisoned but not physically harmed or executed.

Several days ago, police hauled in a spike-haired, punk rock singer at a pro-democracy concert for shouting lyrics deemed critical of the junta.

Prime Minister Prayuth enjoys increasingly good relations with Washington and became a White House guest after U.S. President Donald Trump was inaugurated, in contrast to former President Barack Obama's condemnation of the coup.

The U.S. and Thailand are long-term treaty allies, and sent an increased number of military officials to each other's country during the past year amid Washington's fears that Bangkok may be lured toward supporting Beijing in regional disputes.

During Trump's presidency, the Pentagon has also boosted weapons sales and annual military training with Thailand, including an expanded multinational Cobra Gold exercise staged here earlier this year.

On May 20, for the first time ever, the U.S. 7th Fleet began its 13th Pacific Partnership training exercise in Thailand's waters with a ceremony aboard a Military Sealift Command expeditionary fast transport ship, USNS Brunswick.

The exercise is "the largest annual multilateral humanitarian assistance and disaster relief preparedness mission" and designed "to enhance regional interoperability and disaster response capabilities, increase stability and security in the region, and foster new and enduring friendships across the Indo-Pacific Region," the 7th Fleet said.

Four years after the coup, Mr. Prayuth continues to allow courts to prosecute political opponents for sedition or other serious crimes, including politicians from the main opposition Pheu Thai (For Thais) party who held a critical news conference earlier this month.

Some fear Mr. Prayuth's laws may be used to dissolve the popular Pheu Thai party which headed the coalition government he ousted in his 2014 putsch.

Then-Prime Minister Yingluck Shinawatra was later convicted of "criminal negligence" for administrating a corruption-riddled rice crop subsidy scheme.

She fled Thailand days before receiving a five-year prison sentence, but many of her financial assets were seized.

Her authoritarian brother, former Prime Minister Thaksin Shinawatra, shared a similar fate after being toppled in a 2006 coup, in which Mr. Prayuth participated.

Mr. Thaksin became an international fugitive after being given a two-year prison sentence for corruption in a real estate deal.

The wealthy siblings remain popular among supporters, but it is unclear how much influence they will have if elections are allowed.

The junta orchestrated a 2017 constitution which awards a 250-seat Senate to appointed military officials and other allies to balance an elected House of Representatives' 500 members.

Mr. Prayuth is widely expected to try and remain prime minister after the polls as a constitutionally permitted "outsider," if there is a hung Parliament and he is appointed by the 250 senators plus 125 house members.

Alternatively, he could be elected as a politician if he joins a party.

"I am not a vacuum cleaner," Mr. Prayuth said in April, denying opposition taunts that he was "sucking" and "siphoning" politicians to join him so they could win against poorly-led opposition parties.

"I have not siphoned anyone," Mr. Prayuth said, offering vague statements about whether or not he is maneuvering to stay in power.

The 2014 coup brought peace to Bangkok, bloodied by a 2010 pro-election insurrection which left more than 90 civilians dead and followed by an anti-election insurrection which favored a military solution.

"Whether the military has actually ended this divisive activity however, or merely paused it at gunpoint, remains to be seen," a Bangkok Post editorial said on May 22.

Muzzled by the junta's restrictions against speaking freely about Thailand's politics, critics and local media now criticize the regime's handling of an uneven economy which is among the worst in Southeast Asia.

Coup supporters may be abandoning Mr. Prayuth because of economic problems among indebted middle and lower classes, which could prevent him winning enough votes in an election, columnist Pravit Rojanaphruk wrote.

Mr. Prayuth recently visited some of Thailand's less-developed provinces, where he is least popular.

After offering development programs and other expensive projects, critics said Mr. Prayuth was unfairly doling out tax money and populist policies to lure voters away from his opponents.