The countdown is on to the Fed's rate decision on Wednesday as policymakers begin their two-day meeting. Although the central bank is expected to keep rates unchanged, Wall Street

U.S. stock index futures fell on Monday after President Donald Trump reignited concerns about the effects of a global trade war by introducing new tariffs, while markets awaited the Federal Reserve's monetary policy decision this week.

Trump said he plans to announce pharma tariffs over the next two weeks, his latest on levies that have rattled global financial markets over the past months. The news offset optimism stemming from his order that aimed to reduce the time taken for pharma manufacturing plant approvals.