WASHINGTON, Aug. 20 (Xinhua) -- U.S. President Donald Trump said Tuesday talks are ongoing with the Taliban, but remained non-committal to completely withdraw from Afghanistan after 18 years of futile war.

The 18-year-long U.S. military campaign was "ridiculous," Trump told reporters at the White House.

"We're talking to the government of Afghanistan, we're talking to the Taliban, and we're talking to others," he said.

When questioned whether the United States is ready to completely withdraw, Trump said he is looking at various alternatives.

Trump said Washington was "not supposed to be a police force" in Afghanistan, which was invaded by the United States after the Sept. 11 attacks in late 2011.

Trump's remarks came as the U.S. State Department issued a statement saying Special Representative for Afghanistan Reconciliation Zalmay Khalilzad is departing Tuesday for Qatar and Afghanistan to resume talks with the Taliban.

Khalilzad will meet with Afghan leaders in Kabul, the statement said.

The talks are "part of an overall effort to facilitate a peace process that ends the conflict in Afghanistan," according to the statement.