Trudeau said the 2014 agreement for light armored vehicles, signed by Canada’s previous Conservative government and a Canadian unit of U.S. weapons maker General Dynamics Corp, had been written in such a way that taxpayers would have to pay a large amount of money to end it.

“The contract signed by the previous government ... makes it very difficult to suspend or leave that contract,” Trudeau told the Canadian Broadcasting Corp, saying his Liberal administration was looking at a number of options.

Trudeau said that “I do not want to leave Canadians holding a billion-dollar bill because we’re trying to move forward on doing the right thing.” Trudeau added that he found it “incredibly frustrating” that the terms of the contract with the Saudis meant he could not discuss it in more detail.

The opposition left-leaning New Democrats said on Monday in Parliament that Canada should not be arming the Saudis when they are attacking civilian targets in the war in Yemen. The New Democrats, who will be competing for the same voters as Trudeau in 2019 elections, last week called the Khashoggi matter “the latest addition in a series of horrible acts by Saudi Arabia.”

Trudeau repeated the government’s position that Canada could suspend export permits for the armored vehicles if it determined they had been misused.

German Chancellor Angela Merkel on Monday called the killing a “monstrosity” and vowed to halt German arms exports to Saudi Arabia until the case is cleared up.

Trudeau repeated Ottawa’s condemnation of the murder of Khashoggi, a U.S. resident and critic of the Saudi crown prince who disappeared three weeks ago after entering Saudi Arabia’s consulate in Istanbul.

“Countries around the world need to know that there are things they simply cannot do, and killing a journalist who disagrees with the regime is right up there at the top,” Trudeau said.

Relations between Canada and Riyadh have been tense since a diplomatic dispute over human rights earlier this year. In August, Saudi Arabia froze ties with Ottawa after Canada urged the release of jailed civil rights activists in the kingdom.