(CNBC) U.S. stocks declined on Thursday, pulling the S&P 500 back below 2,000, as concerns about Ukraine overtook upbeat reports on the U.S. economy and the labor market.

“The recent U.S. data is positive, but we’re grinding against the world; it’s hard to decouple for too long,” said Paul Karos, a senior portfolio manager at Whitebox Mutual Funds.

“We only need Ukraine and Russia to flare up to trigger a reason to sell,” said Nick Raich, CEO at the Earnings Scout.

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