On his first full weekday in office, President Donald Trump is expected to sign a series of executive orders that will shake up U.S. participation in international trade deals – notably the North American Free Trade Agreement.

Trump tweeted early Monday morning about his " busy week " that will include "a heavy focus on jobs and national security" as reports surfaced that he is preparing to sign executive orders that will effectively withdraw the U.S. from involvement in the Trans-Pacific Partnership and shake up its participation in NAFTA.

Both moves were generally expected to happen under a Trump presidency, especially the country's withdrawal from a TPP deal that former President Barack Obama helped negotiate. Toward the end of Obama's tenure in the White House, TPP began increasingly looking like a pipe dream against strong Republican opposition.

But the NAFTA retooling, though promised by Trump throughout his presidential campaign, could have more immediate ramifications with Canada and Mexico – two of America's most significant trade partners.

Between January and November 2016 – the most recent month for which data were available – Canada was the top buyer of American exports worldwide, according to the Census Bureau . Mexico was No. 2. Collectively, the two countries accounted for more than 34 percent of the U.S. export market.

Mexico and Canada also combined to account for more than 25 percent of the country's total imports over that window.

Canadian Prime Minister Justin Trudeau last week issued a statement congratulating Trump on his inauguration and highlighting an "enduring partnership" between the U.S. and Canada that "is essential to our shared prosperity and security."

"Together, we benefit from robust trade and investment ties, and integrated economies that support millions of Canadian and American jobs," he said. "We both want to build economies where the middle class and those working hard to join it have a fair shot at success."

Trump, however, has argued that the American middle class has been hurt by the existence of NAFTA, which he says encouraged U.S. companies to offshore labor to Mexico without facing high import taxes. A 2014 study from the left-leaning Economic Policy Institute found that NAFTA's implementation increased the U.S. trade deficit with Canada and Mexico by $160 billion between 1993 and 2013, in the process wiping out more than 850,000 U.S. jobs.

But other research has produced less extreme results when examining NAFTA's impact. A 2015 study from the Congressional Research Service found that "the agreement may have accelerated the trade liberalization that was already taking place" but that "many of these changes may have taken place with or without the agreement."

"Not all changes in trade and investment patterns within North America since 1994 can be attributed to NAFTA, because trade has also been affected by a number of factors," the report said.

The rise of China as a trade behemoth and increased manufacturing automation, for example, have both surfaced as contributing factors to U.S. job losses in recent decades outside of the effects of NAFTA.

The trade agreement was implemented under former President Bill Clinton back in 1994 and has helped drive trade between the U.S., Canada and Mexico. But it has recently seen bipartisan opposition develop, as Trump has hit NAFTA hard in recent months and Sen. Bernie Sanders, I-Vt., lashed out at the deal repeatedly during his run for the Democratic Party's 2016 presidential nomination.

Where the U.S. goes from here with its decades-long trade allies is uncertain. Trump is scheduled to sign executive orders in the Oval Office at 10:30 a.m. EST after a meeting with manufacturing executives – at which time TPP withdrawal and NAFTA renegotiation could be on the table. He said during a swearing-in ceremony for his advisers over the weekend that he and his team "will be starting negotiations having to do with NAFTA" relatively soon.