President Trump said Friday that the United States could end the nearly 19-year war in Afghanistan “very quickly” if he chose to do so but that it would involve killing “tens of millions” of people.

Trump’s comments came at a joint news conference with Australian Prime Minister Scott Morrison as he relayed that Afghanistan — a country of about 37 million people — was among the issues that the two men discussed in their meeting at the White House.

“We’ve been very effective in Afghanistan, and if we wanted to do a certain method of war, we would win that very quickly, but many, many, really, tens of millions of people would be killed, and we think it’s unnecessary,” Trump said. “But Australia’s been a great help to us in Afghanistan.”

He made similar comments in July during an Oval Office meeting with Pakistani Prime Minister Imran Khan. At that point, Trump claimed he could win the war “in a week” but said he did not want to go that route, because “I just don’t want to kill 10 million people.”

He later clarified that he had plans in reserve to drop enormous bombs on the country in an all-out military onslaught.

The U.S. military’s role in Afghanistan has been a continuing sore spot for Trump. Recent developments have left uncertain the administration’s strategy for achieving a political solution to the war and the U.S. troop withdrawals Trump has promised.

Earlier this month, Trump decided to call off a secret meeting he planned with Afghan and Taliban leaders to secure a peace deal, after a U.S. soldier was killed in a Taliban attack.

In late 2017, on the recommendation of his national security team, Trump increased the U.S. troop presence in Afghanistan from around 8,600 to around 14,000.

About 5,400 were to be withdrawn as part of a U.S.-Taliban agreement that was due to be signed after nearly a year of negotiations. In canceling the signing, which Trump had proposed be held at Camp David, he said that the talks were “dead.”

Anne Gearan and Karen DeYoung contributed to this report.