US stock index futures fell on Tuesday, as Washington’s new round of tariffs on some Chinese goods kicked in and after a report that officials from both sides were struggling to decide on the schedule for a meeting this month.

Shares of trade-sensitive industrial bellwethers Caterpillar and Boeing fell 1.5 percent each in premarket trading, while those of Apple fell one percent.

A monthly survey on manufacturing activity by the Institute for Supply Management, due at 10 a.m. ET, is expected to shed some light on the impact of the trade war on the U.S. industrial sector.

The S&P 500 index fell 1.8 percent in August, its biggest monthly drop since May, after escalating US-China trade tensions and the inversion of a key part of the US yield curve, seen as a recessionary signal, drove investors toward safe-haven assets.

The benchmark index, however, ended the week up nearly 3 percent as trade tensions were dialed down following signals that Beijing and Washington would meet in September for talks.

Bloomberg, however, reported on Monday that the two sides were yet to agree on a date for the planned meeting.

The Trump administration on Sunday began collecting 15 percent tariffs on more than $125 billion in Chinese imports, while China began imposing new duties on US crude.

Along with the manufacturing data, investors will also keep a close watch on the monthly jobs report due Friday for clues on the health of the U.S. economy.