Treasury prices rose Monday, pushing yields lower, as protests in Hong Kong underlined geopolitical worries that have weighed on risk assets.

The 10-year Treasury note yield BX:TMUBMUSD10Y tumbled 9.1 basis points to 1.640%, its lowest level since October 2016, while the two-year note yield BX:TMUBMUSD02Y was down 5.1 basis points to 1.578%. The 30-year bond yield BX:TMUBMUSD30Y retreated 11.1 basis points to 2.130%, its lowest level since July 2016. The longer-dated maturity remains only three basis points away from its all-time low.

Debt prices move in the opposite direction of yields.

What’s driving Treasurys?

Demand for safe assets like Treasurys continued to pull global government bond yields lower as investors juggled simmering trade tensions between the U.S. and China, U.K.’s grind toward a no-deal Brexit, and the steady drip of anemic global economic data. The worsening growth backdrop has, in turn, raised expectations that the Federal Reserve will cut rates again in September, following a quarter-point cut in July.

Thousands of protesters rushed into Hong Kong International Airport on Monday, prompting the airport authority to cancel all outbound flights. The protests added to the litany of factors that have bruised investor confidence in recent weeks.

U.S. stocks logged their second straight decline as the Dow Jones Industrial Average US:DJIA recorded a 1.5% loss. Asian equities, however, showed a more mixed picture. Hong Kong’s Hang Seng Index HK:HSI ended lower even as China’s Shanghai Composite CN:SHCOMP posted gains.

See: Predicting what happens next in stocks will get trickier this fall when markets navigate a roller coaster of big events

Read: Dow sinks more than 450 points, loses grip on 26,000 as 10-year Treasury hits 1.63%

What did market participants say?

“There’s no real evidence out against bonds right now,” said Kathryn Kaminski, a portfolio manager at AlphaSimplex, in an interview with MarketWatch. “There’s been a huge flight to safety across many asset classes since last week,” she said.

“You might as well thrown out the fundamentals for the time being, because as long as the globe is this unsettled, money will likely continue to pour into dollar-denominated assets like Treasuries. It almost doesn’t matter whether the data is strong or weak, that earnings continue to surprise to the upside, or that things are probably better than they seem,” wrote Kevin Giddis, head of fixed income at Raymond James.