WASHINGTON -- It was third-time lucky for Justin Trudeau in Washington on Thursday as U.S. President Donald Trump welcomed his "friend" the hard-working Canadian prime minister and offered to help him out of a jam with China.

One year after Trump insulted Trudeau after leaving the G7 in Quebec -- dishonest, weak, meek, mild is how he described him on Twitter -- the president displayed a statesman's grace in welcoming the Canadian leader.

Trump signalled Thursday he will raise the issue of two Canadians detained in China when he meets with the Chinese president next week. And even though he held to his tough talk on tariffs, refusing to rule out using them in the future, he praised his North American neighbours for crafting an excellent new trade agreement.

The aura of restraint that Trump projected came on a tense morning as his administration was seized with responding to Iran's Revolutionary Guard shooting down a U.S. surveillance drone. The move sparked competing and unverifiable accounts over where the downing occurred and deepened a conflict between the U.S. and Iran but Trump was adamant the plane was in international waters.

Trudeau's trip to Washington, including his third Oval Office visit since Trump assumed power in2017, was aimed primarily at pushing the new North American trade agreement over the finish line in both countries.

"He's been a friend of mine. We've worked hard together. We worked, in particular, on the USMCA," Trump said, using the acronym for his preferred name for the new trade pact, the United States-Mexio-Canada Agreement.

After his meeting with Trump, Trudeau announced co-operation on a series of initiatives, include a new push to combat the opioid crisis in both countries. They also agreed to speed up two previous plans to ease the flow of goods and people across the border: a new preclearance plan and a long-planned sharing of information on people entering and exiting the two countries will begin this summer.

Speaking to reporters as he and Trudeau sat in the Oval Office, Trump vowed to do whatever he could do to help Michael Spavor and Michael Kovrig when he meets China's President Xi Jinping at next week's G20 leaders' summit in Japan, if Trudeau -- as expected -- asks for his help.

The two Canadians have been languishing behind bars in China since shortly after Canada arrested high-tech executive Meng Wanzhou late last year at the behest of U.S. authorities.

Canada has been caught in the crossfire after the RCMP arrested Meng last December in Vancouver, where she awaits extradition south of the border to face allegations of fraud in violating Iran sanctions.

Trudeau doesn't have a planned meeting with Xi, unlike Trump. The U.S.-China meeting next week is focused on a trade deal.

"I'll represent him well, I will tell you," Trump said. "We'll see what happens, but anything I can do to help Canada I will be doing . . . I would, at Justin's request, I will actually bring it up."

Trudeau said he and Trump had an "extended conversation" about the situation Canada finds itself in with China, which includes blocking imports of Canadian canola and pork. But what Trump will say to Xi isn't clear -- all Trudeau would say is that he expects Kovrig and Spavor to be on the agenda for the Trump-Xi meeting.

Conservative foreign-affairs critic Erin O'Toole said it is about time someone talks to Xi about the situation.

"After half a year of inaction and bungling by the Liberals, the crisis will finally be raised directly with the Chinese president, but it will take the United States to make our case. While this is a positive step, it is frustrating Trudeau let the crisis deepen over half a year," said O'Toole.

Trump and Trudeau projected genuine enthusiasm for the hard-fought completion of a new North American trade deal.

Canada has started the ratification process, with legislation making its way through Parliament. Lawmakers in Mexico voted Wednesday in a landslide to ratify the deal, which Trudeau said he was pleased to see.

But now Trump needs to persuade his Democratic opponents in the House of Representatives -- in particular Speaker Nancy Pelosi -- to allow the actual start of the ratification of the USMCA.

Pelosi and her fellow Democrats want stronger enforcement mechanisms for the deal's new labour and environmental provisions.

Trump sounded upbeat in the Oval Office.

"Let's see what happens, but I really believe that Nancy Pelosi and the House will approve it, I think the Senate will approve it rapidly," the president said. "I think Nancy Pelosi is going to do the right thing."

Trump also said it was a "terrific thing" that Trudeau was to make the rounds on Capitol Hill with Pelosi and the U.S. Senate majority leader Mitch McConnell.

(The meeting with McConnell, the Senate's top Republican, was cancelled because of the U.S.-Iran situation but his support for the new NAFTA is all but a given. Trudeau spoke with him by phone before leaving Washington on Thursday night.)

Speaking on Capitol Hill next to Trudeau, Pelosi said she looked forward to a "lively discussion" on global security issues and the economic relationship between the two countries, particularly regarding trade.

Though Trudeau made clear he wants to stay out of U.S. domestic political wrangling, he reaffirmed his view that it is a done deal that can't be reopened because it could lead to "worse outcomes for Canadians and for Canada."

"We recognize, however, that the U.S. is going through its process and we remain alert to potential challenges and opportunities that may come through that process."

PMJT and POTUS meet in the Oval Office. Ratification of USMCA is top agenda item. pic.twitter.com/0SqngEVJ5S — Glen McGregor (@glen_mcgregor) June 20, 2019