After setting a series of new all-time highs in March, April is offering a more difficult first week for the S&P/ASX 200 Index (ASX: XJO).

In this shortened holiday trading week, the benchmark index closed down 0.1% on Tuesday before plunging 1.3% on Wednesday.

Yesterday saw a reprieve, with the index closing up a healthy 0.5%, bringing it back to a 12.9% six-month gain.

So, why is the ASX 200 reversing course again and tumbling 0.9% in morning trade today?

It's not just the ASX 200 under selling pressure today.

Overnight the S&P 500 Index (SP: .INX) closed down 1.2%. Notably, the S&P 500 was well into the green for most of the day, before plummeting 1.8% in the final two hours of trade.

It was a similar picture on the Nasdaq Composite Index (NASDAQ: .IXIC). The tech-heavy index lost 2.3% in the final two hours of trade to close the day down 1.4%.

And the ASX 200 is facing the same combination of headwinds today that dragged down US markets while most of us were asleep.

The first bugbear dragging on stock markets is becoming a familiar refrain for ASX 200 investors.

Namely sticky inflation and the resulting potential of delayed and fewer interest rate cuts.

The latest round of jitters looks to have been stoked by US Federal Reserve Bank of Minneapolis president Neel Kashkari.

Kashkari said the US' inflation data in January and February were "a little bit concerning". He added that the Fed will want to be more confident inflation is on track to return to its 2% target range before lowering interest rates.

And he likely sent US and ASX 200 investors to their sell buttons when he added that rate cuts might not be needed "at all".

According to Kashkari (courtesy of Bloomberg):

In March I had jotted down two rate cuts this year if inflation continues to fall back towards our 2% target. If we continue to see inflation moving sideways, then that would make me question whether we needed to do those rate cuts at all.

Atop fears that interest rate cuts may be longer in coming and fewer in number, ASX 200 investors also appear concerned over a potential serious escalation in the Middle East conflicts.

Commenting on the sudden retrace in US stock markets earlier today, National Australia Bank Ltd (ASX: NAB) said (quoted by The Australian Financial Review), "US equities opened higher and retained their initial gains until an hour or so ago."

NAB continued:

Sentiment was dented following news of a security cabinet meeting in Israel following which Israeli Prime Minister Netanyahu said that his country will operate against Iran and its proxies and will hurt those who seek to harm it.

And if investors need any more uncertainty, there's the US jobs report, which comes out at 11:30am AEDT today.

US employment is broadly expected to remain strong with fewer layoffs and more hirings. If the data surprises to the upside, it could be a case of 'good news is bad news'. Meaning good news for the US economy and workforce could delay any Fed rate cuts.

And that could throw up another medium-term headwind for US stocks and the ASX 200.