U.S. Secretary of Homeland Security Jeh Johnson speaks during a news conference in 2015 at the headquarters of U.S. Immigration and Customs Enforcement in Washington. (Alex Wong/Getty Images)

President-elect Donald Trump’s vow to begin deporting undocumented immigrant criminals means confronting two of the United States’ biggest trading partners as well as dozens of other countries, allies and foes that have refused to cooperate on the issue or that significantly delay the repatriation process.

The State and Homeland Security departments list 23 countries as “uncooperative” for refusing to take back many of their citizens who came to the United States — in some cases decades ago — and have been ordered deported after being convicted of felonies.

Cuba tops the list, followed by China, Somalia, India and Ghana.

Traffic offenses, especially driving under the influence of alcohol, accounted for the largest category of convictions, followed by drug offenses and larceny.

In most cases, the immigrants, who do not hold U.S. citizenship, have no passport or birth certificate to prove their original citizenship, and their home countries refuse to issue new travel documents.

Once they have completed prison time in the United States, they cannot continue to be held pending deportation, following a 2001 Supreme Court decision that found that the United States cannot detain them indefinitely. The court ruled that they must be released within 180 days of serving their sentence, even if their home countries won’t accept them.

An additional 62 countries — led by Vietnam, Haiti, Brazil, Pakistan and Senegal— are accused by the U.S. government of dragging their feet in issuing travel documents. And without valid travel papers, authorities here are unable to put people on planes home.

This list includes allies such as Slovenia, the Czech Republic, Greece, Sweden and Turkey, as well as foes such as Syria and Russia.

Absent from both lists is Mexico, which has been the focus of some of Trump’s most heated statements about undocumented immigrants who commit crimes.

During the presidential campaign and in interviews after the election, Trump said he would make it a priority to track down and deport as many as 2 million to 3 million undocumented immigrants with criminal records.

“What we are going to do is get the people that are criminal and have criminal records — gang members, drug dealers, we have a lot of these people, probably 2 million, it could be even 3 million,” he said in an interview with CBS’s “60 Minutes.” “We are getting them out of our country or we are going to incarcerate. But we’re getting them out of our country; they’re here illegally.”

Many immigration experts say the numbers are probably not nearly that high. In 2012, the Obama administration estimated that 1.9 million people in the country were “removable criminal aliens.” But that number includes people with green cards, who are legal residents, and people convicted of nonviolent crimes. The Migration Policy Institute, a nonpartisan research organization, estimates that about 820,000 of 1.9 million deportable criminals were undocumented.

The State Department has played hardball twice to force repatriations, both times targeting small countries.

In 2001, the United States imposed a visa ban on government officials from Guyana, a South American country that had delayed receiving deportees. It complied within months.

In September, the State Department stopped issuing visas to government officials in Gambia, an African country with about 1,200 citizens in the United States who have final deportation orders. The following month, according to a spokesman for Immigration and Customs Enforcement, the Gambian Embassy issued travel documents to 11 citizens.

Gambian officials say they have complied and are hopeful that the visa ban will be lifted soon.

“We could not identify them, that they really were Gambians,” said Hamba Manneh, a consular officer with the embassy. “We asked ICE to send us another list. We’ve issued travel documents, and now they are sending them back home.”

Cracking down on countries that are blocking or delaying deportations can invite reciprocal measures, affecting international business, tourism and human rights, said Doris Meissner, a former commissioner of the Immigration and Naturalization Service. As a result, the State Department has tried to negotiate with countries reluctant to take back their citizens.

“Typically, the country would retaliate and say, ‘If you’re not issuing visas to us, we won’t issue visas to you,’ ” said Meissner, now a fellow at the Migration Policy Institute. “Or they will suspend visas they already have issued. Right away, it puts a lot of stuff into play that hurts the United States. Business travel, the transfer of executives, foreign students going back and forth, tourism.”

But some lawmakers want a more forceful response. Senate Judiciary Committee Chairman Charles E. Grassley (R-Iowa) has accused the Obama administration of failing to use its authority to stop issuing visas as leverage to force cooperation.

“Lives are being lost, the public’s safety is at risk and American families are suffering,” he said in a June letter to Homeland Security Secretary Jeh Johnson. “It cannot continue.”

Chuck Ambrose, a retired federal prosecutor in Kansas City, said he has dealt with the failure to act. In 2005, he said he prosecuted an Afghan citizen who conspired to distribute cocaine, but after his release from prison, the man was not repatriated. Ambrose said the Afghan subsequently took part in a vicious assault on a Marine, and Ambrose had to prosecute him again in 2009.

“Among the 23 countries that are listed, two stuck out at me — Afghanistan and Iraq,” Ambrose said. “I cannot imagine two nations we would have more leverage over. . . . I think our State Department should grow some teeth, rather than flapping their gums.”

In testimony before the House Oversight Committee this summer, Michele Thorne Bond, assistant secretary for consular affairs, said her staff and Secretary of State John F. Kerry raised the issue in meetings with some of the laggard countries. But she said repatriations of convicted criminals sometimes get tangled up with conflicting interests.

Cuba, she said, will consider taking back its citizens only if there are changes to U.S. policy on Cuban migration. China links its cooperation with the return of fugitives accused of criminal acts in China, but who may, in fact, have fled the country for political reasons.

Bond also noted that Chinese visitors contribute $29 billion to the U.S. economy annually, and 2,000 American families adopted children from China last year — all of which could be affected by a dispute with China.

India, too, is deeply intertwined with the United States and, for instance, sends 130,000 students here each year.

Officials at the Indian Embassy said they are willing to take back their nationals — once offered proof of citizenship.