President-elect Trump on Tuesday refused to commit to not using the U.S. military to gain control of the Panama Canal, after vowing last month to take over operation of the key passageway.

Trump was questioned during a press conference at Mar-a-Lago about his recently targeting the canal as well as Greenland for possible American expansion and if he would say he would not use the military to gain control of it.

“I’m not going to commit to that. It might be that you have to do something,” Trump said. “Look, the Panama Canal is vital to our country, it’s being operated by China, China. And we gave the Panama Canal to Panama, we didn’t give it to China.”

New York Times reporter David Sanger questioned the president-elect on if he can if “assure the world” that “you are not going to use military or economic coercion.”

“No,” Trump replied.

He was then questioned if he could elaborate on his plans to increase U.S. territorial holdings.

“I can’t assure you you’re talking about Panama and Greenland, no, I can’t assure you on either of those two. But I can say this, we need them for economic security. The Panama Canal was built for our military,” Trump said.

He was later questioned on if he has drawn up plans for acquisition and replied that he’s “not at that stage,” noting that he hasn’t taken office yet.

He later committed to not using military force to acquire Canada, which he has referred to as a potential 51st state, but added that he would use “economic force,” adding “we don’t need anything they have” and the U.S. shouldn’t be protecting its northern neighbor.

The president-elect criticized the late President Carter over the sale of the Panama Canal, which was once controlled by the U.S. It has been under Panamanian control for nearly 25 years under a deal pushed by Carter in 1977.

“Giving the Panama Canal is why Jimmy Carter lost the election, in my opinion, more so maybe than the hostages,” he said, referencing the Iran hostage crisis.

The president-elect added that it’s “inappropriate” to talk about that now because it’s “a bad part of the Carter legacy.”

Carter died on Dec. 29 and he will lie in state at the U.S. Capitol starting on Tuesday.

“He was a good man, I knew him a little bit,” Trump said, adding that “giving the Panama Canal to Panama was a big mistake.”

Earlier in the press conference, Trump argued that China is running the canal. China has invested heavily in Panama, including in a number of construction deals, and manages two of Panama’s five main ports.

He also called the Panama Canal “a disgrace” and railed against Carter for giving it to them “for $1.”

“We gave it away for $1, but the deal was they have to treat us fairly,” he said, arguing that the U.S. gets charged more than others. “They laugh at us because they think we’re stupid, but we’re not stupid anymore.”