U.S. stocks ended mixed on Monday as investors were watching closely the latest geopolitical issues.

The Dow Jones Industrial Average rose 29.24 points, or 0.13 percent, to 21,703.75. The S&P 500 gained 2.82 points, or 0.12 percent, to 2,428.37. The Nasdaq Composite Index was down 3.40 points, or 0.05 percent, to 6,213.13.

With no key data came out on Monday, Wall Street were awaiting the closely-watched speech by U.S. President Donald Trump on Monday night about the country's strategy for the war in Afghanistan.

Besides, investors also kept an eye on the development of geopolitical tensions between the United States and the Democratic People's Republic of Korea (DPRK).

The market was further under pressure amid political uncertainty in the White House.

Trump announced earlier this month that he was disbanding both the Manufacturing Council and Strategy and Policy Forum, as business leaders resigned from the council over Trump's remarks on Charlottesville violence. It was also reported on Friday that Trump had removed Steve Bannon as his chief strategist.

Analysts said recent turmoil in Washington spurred market concerns about whether the Trump administration is able to push through its economic agenda.

Moreover, expectations for tighter monetary policy in the U.S. have been dampened recently by soft inflation data. Market expectations for a rate hike in December are just 41 percent, according to the CME Group's FedWatch tool.