The yen rose on Monday, driven by an appetite for safe-haven assets as Washington and Beijing imposed additional tariffs on each other's exports, adding to the gloom hanging over the global economic outlook.
Gold, which tends to be bought with the yen during times of economic uncertainty, also rose on Monday by the most in almost a week as investors were drawn to so-called risk-off trades.
In offshore trade, the Chinese yuan fell toward the lowest since international trading in 2010 in a sign of concern about China's slowing economy.
Investors will closely monitor China's stock markets and how the People's Bank of China fixes onshore yuan trading in Asian morning trade as a broader gauge of risk appetite, an important factor behind market swings in recent weeks.
"The tariffs suggest we are not going to see a very market-friendly open this week," said Rodrigo Catril, a senior foreign-exchange strategist at National Australia Bank in Sydney.