Crude oil prices attempted to rebound on Monday, rising in the morning after Saudi Arabia signaled production cuts.

But the US president undercut that headline quickly, sending crude prices plunging with a Tweet, expressing the hope that Saudi Arabia will not cut output.

The Trump administration had earlier in the year driven prices higher with the threat of sanctions on Iranian oil exports, but then changed that narrative last week when waivers were announced for eight nations, including the largest importers of Iranian oil.

Prices have since tanked, entering bear-market territory, helping prompt OPEC to consider production cuts. Concerns that demand may be slipping amid slower global economic growth have also weighed on prices.