Martin Ferris, a member of Ireland’s Parliament, had a full schedule.

He was supposed to arrive in Boston on Thursday and head up to Lynn, where the mayor, Tom McGee, was going to show him around. On Friday, he was going to meet hundreds of supporters of his Sinn Féin political party at Florian Hall in Dorchester.

On Saturday, he was going to head out to Springfield, which is like going to home Kerry because half of Hungry Hill hails from the Kingdom, as they call it back in Ireland. His old friend Richie Neal, the congressman, and Domenic Sarno, the mayor, were going to squire him around Springfield, and the John Boyle O’Reilly Club would be buzzing.

Alas, when I spoke to Ferris on Thursday afternoon, he was stuck at home in Kerry because the US government had not given him permission to enter the United States, and so his American tour, timed to St. Patrick’s Day, was ruined.

This is the same US government, mind you, that has previously given Martin Ferris a visa on 11 previous occasions over the last two decades without a problem.

The last time Ferris flew to Boston, two years ago, he was detained and questioned, first in Dublin, then in Boston.

In Dublin, US immigration officials questioned him about what he was going to do in Boston, even though he had given the US embassy in Dublin his complete itinerary in order to get a visa in the first place. As a result, he missed his flight.

Then when he landed in Boston on a later flight, FBI agents were waiting for him. They questioned him for almost three hours. They took his cellphone and went through and presumably took down all his contacts. They were asking him whether he knew any dissident Irish republicans and whether he was going to meet with any while in Boston.

Which goes a long way toward confirming the bias that the FBI couldn’t find a gambler in a mahjong den.

The last people Martin Ferris would want to talk to, or who would want to talk to him, are dissident republicans who have spent the last two decades trying to restart a war that Martin Ferris helped end. Dissident republicans would rather kill Martin Ferris than talk to him.

Martin Ferris used to be a commander in the Provisional Irish Republican Army. A terrorist, according to the US, British, and Irish governments. But some 30 years ago, after serving time in prison for getting caught on a boat loaded down with tons of weapons assembled by Boston gangsters, Ferris became part of the Irish republican leadership pushing for peace.

Because he was known as a hardliner, Ferris’s support for the strategy aimed at replacing physical force republicanism with one that would seek a united Ireland through peaceful, democratic means was crucial in winning over the most recalcitrant of IRA fighters. Dissident republicans hate him, and the feeling is mostly mutual.

Ferris is a case study in the remarkable transformation from gunman to statesman, a transformation that the US government spent untold time and resources and diplomatic capital encouraging. As a reward for his being an integral leader in the peace process, Ferris was regularly allowed to travel here since the 1998 Good Friday Agreement ended what the Irish, in their penchant for understatement, called The Troubles. Like other former members of the IRA, he was required to obtain a visa from the State Department, which was a mere formality.

Theoretically, Ferris’s inability to get a visa this time could be a case of an unforseeable backlog, or bureaucratic incompetence, something not unknown to this administration or previous ones. But let’s not kid ourselves. This is something that could be fixed with a phone call.

Something changed, beginning two years ago under the Obama administration, when he was harassed by Immigration in Dublin and the FBI in Boston. At least they let him in. Now, under the Trump administration, he can’t even get in the country.

Just the kind of message the United States wants to send to other combatants in other conflicts the US is trying to end: Put your guns down, make peace, and we’ll be nice to you for a while. But when it suits our purposes, we’ll kick you to the curb.

Now that’s what I call a foreign policy.

Ferris had planned to fly to the United States last week, with stops in Florida, Kentucky, and Ohio, before arriving in Boston on Thursday. He kept checking every day this week, hoping at least to get the visa in time to make the Massachusetts portion of his trip. But no luck.

Ferris was subdued and surprisingly sanguine when I spoke to him.

He said he had applied for a visa nine weeks ago and was told by embassy officials in Dublin that it would take approximately six weeks, which is about standard.

When I asked him if he thought this was a deliberate snub by the US government, Ferris replied, “I don’t know. I hope not.’’

Martin Ferris has become a real diplomat in his old age. He isn’t the only Sinn Féin official who couldn’t get a visa to travel for St. Patrick’s Day events this year. Richard McAuley, the longtime aide to former Sinn Féin leader Gerry Adams, also got stiffed.

Mary Lou McDonald, who last month succeeded Adams as Sinn Féin’s leader, didn’t need a visa to travel, nor did Ferris’s daughter, Toireasa, a Sinn Féin official, because they were never in the IRA and don’t have records.

Toireasa Ferris made it to Boston this week and will carry on solo at the events to which she was supposed to accompany her father.

“I’m very disappointed,’’ Martin Ferris said. “Disappointed not just for the people in Boston and Springfield and Lynn, but for the people in Tampa and Cincinnati and Kentucky I was going to meet.’’

I’m disappointed, too. Disappointed that a government, our government, which did so much to bring peace to and sustain peace in Ireland, something for which it should be proud, now sees fit to treat so shabbily someone who believed our government’s promise that if he traded his gun in for a pen, he would be treated with respect.

Some respect.

Kevin Cullen is a Globe columnist. He can be reached at cullen@globe.com.