Among the roughly 1,350 workers laid off at the State Department last week were senior analysts in the bureau of intelligence, including people who specialize in Russia and Ukraine, according to several current and former U.S. officials.

The firings mean a loss of expertise as President Trump renews his efforts to settle the war between Russia and Ukraine, one of his top foreign policy goals. On Monday, Mr. Trump announced a new plan to send arms to Ukraine and threatened harsh economic penalties against Russia unless it agreed to a cease-fire.

The layoffs were among several at the department’s Bureau of Intelligence and Research, commonly known as INR. The bureau employs no spies and does not conduct surveillance of its own, but provides analysis about world events to help guide U.S. diplomacy.

It is unclear how many intelligence analysts were dismissed on Friday, and the bureau still retains workers who will focus on Russia and Ukraine after the merger of two offices within INR. Ellen McCarthy, a former State Department official who led the bureau for two years during Mr. Trump’s first term, said that paring jobs from it was “shortsighted.”

“This isn’t just about jobs, it’s about weakening a critical capability at exactly the wrong time,” Ms. McCarthy wrote in a post on LinkedIn. “The world is more complex, more volatile, and more interconnected than ever.” She added: “We should be investing in INR, not shrinking it.”