After one of the quietest summers for the stock market in years, Wall Street’s fear gauge has once again shot higher as investors fret that a trade standoff between the U.S. and China could escalate further.

The Cboe Volatility Index

VIX, better known as the VIX, or Wall Street’s “fear gauge,” traded as high as 22.76 on Tuesday, its highest intraday level since May 23, when it traded as high as 25.53, according to Dow Jones Market Data. By the time the market closed, the VIX had moved well off its earlier highs. The index ended the day above 20, a level with some significance.