President-elect Joe Biden and Vice President-elect Kamala Harris received a national security briefing from their team of experts on Monday.
Biden and Harris will deliver brief remarks on the subject later Monday.
Reporters were allowed in for a short period, during which Biden stressed the importance of the country's recommitting to global alliances after Trump's presidency.
"The past four years we've seen a lot of damage to American global leadership and traditional alliances, democracy under assault, and our security jeopardized by a go-it-alone approach in this administration. And the truth is the challenge we face today, can't be solved by any one country acting alone," he said.
Harris thanked those participating for their service and commitment to the country.
Among those participating were Secretary of State-designate Tony Blinken, Defense Secretary-designate Lloyd Austin, incoming National Security Adviser Jake Sullivan and Avril Haines, Biden's pick for director of national intelligence.