NEW YORK (AP) — President Donald Trump’s barrage of tariffs has quickly strained the United States’ longstanding relationship with Canada over the last year.

Since taking office in January, Trump has threatened Canada’s economy and sovereignty with steep import taxes on its goods. He’s even claimed that America’s neighbor to the north could be “the 51st state.”

Here’s a timeline.

January

On his first day in office, Trump says he expects to put 25% tariffs on imports from Canada starting on Feb. 1.

February

Trump signs an executive order to impose 25% tariffs on imports from Canada starting Feb. 4 — invoking this power by declaring a national emergency, ostensibly over undocumented immigration and drug trafficking.

March

Trump’s 25% tariffs on imports from Canada go into effect on March 4, though he limits the levy on Canadian energy to 10%. In response, Trudeau announces counter tariffs on more than $100 billion of American goods over the course of 21 days.

But Trump soon grants a one-month exemption on these tariffs for U.S. automakers

Worldwide, Trump’s new steel and aluminum tariffs — which now tax imports of both metals at 25% — still go into effect March 12. Canada then imposes retaliatory tariffs.

April

Trump announces his long-promised “reciprocal” tariffs on nearly all of America’s trading partners April 2, but doesn’t unveil additional levies on Canada.

The White House says USMCA-compliant imports can continue to enter the U.S. duty-free — and once Trump’s demands on immigration and drug trafficking are satisfied, the tariff on the rest of their imports may drop from 25% to 12%.

Trump later signs an executive order to relax some of his auto tariffs, but relief is limited.

May

On May 28, the U.S. Court of International Trade blocks Trump from imposing the bulk of his most sweeping tariffs — ruling that the president overstepped his authority when he invoked an emergency powers law to slap import taxes on almost every country in the world, including levies imposed on Canada. But just a day later, a federal appeals court temporarily halts the order.

June

Worldwide, Trump’s new 50% tariffs of nearly all foreign steel and aluminum take effect June 4. Carney later threatens to impose new tariffs on U.S. steel and aluminum starting in July, pending progress of trade talks. The Canadian Prime Minister says that Trump’s trade war is running the risk of a global recession.

July

Trump sends a letter to Canada warning that the U.S. will heighten its tariffs against the country to 35% starting Aug. 1, up from 25% imposed in March — although some goods are currently protected under the USCMA pact. At the time, Carney maintains that Canada will continue to work towards a deal by the new deadline.

August

Trump’s heightened 35% tariff rate on a range of Canadian goods take effect on Aug. 1. Globally, the U.S.’s new 50% levy on imported copper also kicks in.

Later in the month, Carney says that Canada will drop many of its retaliatory tariffs to match U.S. exemptions for goods covered under the USMCA pact.

Meanwhile, a federal appeals court rules that Trump illegally used emergency powers to impose sweeping tariffs worldwide — but leaves the import taxes in place for now. The Trump administration later appeals to the Supreme Court.

October

For trading partners worldwide, Trump’s new tariffs on kitchen cabinets, bathroom vanities and upholstered wooden furniture went into effect on Oct. 14, starting with a 25% levy on many of these imports. On Oct. 22, Carney outlines plans for Canada to double its non-U.S. exports in the next decade. He says the new levies are causing a chill in investment. A day later, Trump says he’s ending “all trade negotiations” with Canada — in an abrupt move over a television ad opposing U.S. tariffs, which Trump claims misstated the facts and was aimed at influencing court decisions. The ad was paid for by the Ontario provincial government, not the Canadian federal government. Ontario Premier Doug Ford later says he’s pulling the TV ad so trade talks may resume.