After adding to the uproar over NFL players who protest during the national anthem, President Donald Trump mostly stuck to hockey in honouring the Stanley Cup-winning Pittsburgh Penguins on Tuesday, calling them "true champions and incredible patriots."

Trump welcomed the Penguins into the Oval Office and celebrated their second consecutive championship in the East Room of the White House. He singled out the achievements of playoff MVP Sidney Crosby, Evgeni Malkin and Phil Kessel, among others.

Trump has grabbed a number of sports headlines in recent weeks, including his criticism of NFL players for kneeling during the anthem and his decision to disinvite the NBA champion Golden State Warriors from the White House for the type of championship visit made by the Penguins, the New England Patriots, the Chicago Cubs and the Clemson University football team.

U.S. President Trump showers Sidney Crosby with compliments at the White House on Tuesday. 1:06

"Everybody wanted to be here today," Trump said of the Penguins. "And I know why."

Hours after tweeting that the tax code should be changed to punish NFL teams over the anthem issue, Trump joked that Penguins co-owner Ron Burkle should help him renegotiate NAFTA but largely avoided any talk about other sports.

Why is the NFL getting massive tax breaks while at the same time disrespecting our Anthem, Flag and Country? Change tax law! —@realDonaldTrump

"It's been an honour to have them all here," Trump said.

Crosby has said on multiple occasions that the team's decision to go to the White House was not politically motivated. Coach Mike Sullivan said the Penguins understand the circumstances of their visit and that he didn't feel like Trump was using them as a political prop.

"We've stated clearly from the get-go that our visit to the White House is not political," Sullivan said. "Nobody's choosing a side. Nobody's taking a stand. We are simply honouring our championship and the accomplishments of this group of players over this season or the last two seasons."

The U.S. President celebrated the Penguins back-to-back Stanley Cup wins at the White House on Tuesday. 1:20

Of the 18 players who won the Cup last season and are still with the Penguins, seven are American: Kessel, Ian Cole, Brian Dumoulin, Jake Guentzel, Bryan Rust, Chad Ruhwedel and Conor Sheary. Crosby and six others are Canadian, two are Swedish, one is Russian and one is Finnish.

'They're world champions'

Trump congratulated the Penguins for being the first back-to-back Cup champions since the Detroit Red Wings in 1997 and 1998, complimented co-owner Mario Lemieux's golf game and drew boos when he referenced Pittsburgh's upcoming game against the rival Washington Capitals. He said he expected the Penguins to be back at the White House next year.

"This is really a truly great group of world champions," Trump said. "That's what they are. They're world champions."

Sullivan, the only member of the team who spoke to reporters after the visit, said "zero" politics came up with Trump behind closed doors.

With the Pittsburgh Penguins deciding not to follow in the Golden State Warriors footsteps and decline and invite to the White House, Rob Pizzo counts down 5 other times a White House visit made headlines. 1:45

Tampa Bay Lightning forward J.T. Brown, one of 18 black players in the NHL, became the first hockey player to engage in an anthem protest when he raised his fist while standing on the bench before a game Saturday night. Sullivan said he wouldn't have a problem if one of his players took a knee during the national anthem.

"We're very respectful of anyone's right to protest or demonstrate as they see fit," said Sullivan, who is American. "We're very respectful of it."

Team presents Trump with gift

The Penguins had one black player on their championship team, Trevor Daley, but he signed with Detroit in the offseason and did not travel to Washington because the Red Wings were playing in Dallas. They currently have one black player, Ryan Reaves, but he and others acquired over the summer who didn't win the Cup also did not go to the White House.

Trump has called on NFL owners to fire players who don't stand for the anthem and urged fans to boycott games in a series of tweets. He tweeted that he instructed Vice President Mike Pence to leave a game between the San Francisco 49ers and Indianapolis Colts on Sunday if there were any anthem protests, which Pence did.

NHL commissioner Gary Bettman told The Associated Press recently that said he respects players' views on political and social issues and "people are going to have to decide what makes them comfortable." Bettman said social issues "are a matter of individual belief and individual choice."

Sullivan also said the team presented Trump with an undisclosed gift.