Oil prices surged and United States equities fell sharply Friday as officials in Washington said Moscow could attack Kyiv soon.

Markets lurched during a briefing by U.S. National Security Adviser Jake Sullivan, who said a Russian invasion could "begin at any time," including during the ongoing Beijing Winter Olympics.

Near 7:15 p.m. GMT, the broad-based S&P 500 was down 1.5% at 4,438.89. The benchmark West Texas Intermediate oil future was up about 4% to $93.48 per-barrel.

Shares of weapons makers also moved higher, including Lockheed Martin, which gained 2.8% and Northrop Grumman, which rose 4.1%.

Investors had become less worried about an imminent invasion of Ukraine in recent days following Western diplomacy with Russian President Vladimir Putin, said Art Hogan, chief strategist at National Securities.

But the shift in tone Friday from the Biden administration prompted a sell-off ahead of the weekend market closure.

"If the market hasn't fully priced in the risk of a Russian incursion into Ukraine, it may start to do that," said Hogan, adding that markets were in a "risk-off" mode.