U.S. import prices posted their biggest gain in seven months in August amid a spike in petroleum costs.
Treasury yields rose slightly, with the benchmark 10-year yield at 2.24 percent and the two-year yield at 1.401 percent.
Wall Street also looked to the United Nations, where U.S. President Donald Trump tried to rally members to confront threats like North Korea. In a speech to the U.N. General Assembly, Trump said "North Korea's reckless pursuit of nuclear weapons and ballistic missiles threatens the entire world with unthinkable loss of human life."
Tension between the U.S. and North Korea has escalated recently. Last week, the isolated Asian nation launched a missile that flew over Japan before landing in the sea.
The launch took place after the U.N. Security Council unanimously imposed a ban on North Korea's textile exports and capped its crude oil imports.
However, "a new war on the Korean Peninsula seems very unlikely at this time," said Paul Christopher, head global market strategist at the Wells Fargo Investment Institute, in a note last week.
"The South Koreans we spoke with said they did not worry about a nuclear attack, and they widely dismissed a preemptive U.S. attack on North Korea," Christopher said. "We heard the same thing in China and in Japan, mainly because they perceive a low potential reward with a high risk."
Investors also kept an eye on tax-reform prospects, after Sen. Bob Corker told reporters that GOP lawmakers had reached a tentative tax reform-budget deal. Wall Street has been waiting for clarity on tax reform since Trump won the president.
The market's reaction to the news, however, was muted.
"The market is waiting for something more concrete at this point before really responding," said Tim Alt, director of rates and currencies at Aviva Investors. "And with the Fed on tap for tomorrow, nobody wants to make any big bets."