Multi-exposure photo taken on Feb. 12, 2020 shows NATO Secretary General Jens Stoltenberg addressing a press conference during a NATO defense ministers meeting at the NATO headquarters in Brussels, Belgium. NATO Defense Ministers met in Brussels on Wednesday to begin the two-day meeting. (Photos: Xinhua)

U.S. Secretary of Defense Mark Esper (L) talks with his British counterpart Ben Wallace before the group photo ceremony at the NATO headquarters in Brussels, Belgium, Feb. 12, 2020. NATO Defense Ministers met in Brussels on Wednesday to begin the two-day meeting.

NATO Secretary General Jens Stoltenberg addresses a press conference during a NATO defense ministers meeting at the NATO headquarters in Brussels, Belgium, Feb. 12, 2020. NATO Defense Ministers met in Brussels on Wednesday to begin the two-day meeting.

NATO Secretary General Jens Stoltenberg (R) addresses a press conference during a NATO defense ministers meeting at the NATO headquarters in Brussels, Belgium, Feb. 12, 2020. NATO Defense Ministers met in Brussels on Wednesday to begin the two-day meeting.

Canadian Defense Minister Harjit Singh Sajjan attends a NATO defense ministers meeting at NATO headquarters in Brussels, Belgium, Feb. 12, 2020. NATO Defense Ministers met in Brussels on Wednesday to begin the two-day meeting.

NATO Secretary General Jens Stoltenberg (C) chairs a NATO defense ministers meeting at the NATO headquarters in Brussels, Belgium, Feb. 12, 2020. NATO Defense Ministers met in Brussels on Wednesday to begin the two-day meeting.

A NATO defense ministers meeting is held at the NATO headquarters in Brussels, Belgium, Feb. 12, 2020. NATO Defense Ministers met in Brussels on Wednesday to begin the two-day meeting

U.S. Secretary of Defense Mark Esper (R) talks with NATO Secretary General Jens Stoltenberg before the group photo ceremony at the NATO headquarters in Brussels, Belgium, Feb. 12, 2020. NATO Defense Ministers met in Brussels on Wednesday to begin the two-day meeting.

North Macedonia's Defense Minister Radmila Sekerinska (R) arrives for a NATO defense ministers meeting at the NATO headquarters in Brussels, Belgium, Feb. 12, 2020. NATO Defense Ministers met in Brussels on Wednesday to begin the two-day meeting.

NATO Secretary General Jens Stoltenberg (R) addresses a press conference during a NATO defense ministers meeting at the NATO headquarters in Brussels, Belgium, Feb. 12, 2020. NATO Defense Ministers met in Brussels on Wednesday to begin the two-day meeting.

British Defense Secretary Ben Wallace arrives for a NATO defense ministers meeting at the NATO headquarters in Brussels, Belgium, Feb. 12, 2020. NATO Defense Ministers met in Brussels on Wednesday to begin the two-day meeting.

German Defense Minister Annegret Kramp-Karrenbauer (L) arrives for a NATO defense ministers meeting at the NATO headquarters in Brussels, Belgium, Feb. 12, 2020. NATO Defense Ministers met in Brussels on Wednesday to begin the two-day meeting.

German Defense Minister Annegret Kramp-Karrenbauer (L) talks with her Croatian counterpart Damir Krsticevic before a NATO defense ministers meeting at the NATO headquarters in Brussels, Belgium, Feb. 12, 2020. NATO Defense Ministers met in Brussels on Wednesday to begin the two-day meeting.

German Defense Minister Annegret Kramp-Karrenbauer arrives for a NATO defense ministers meeting at the NATO headquarters in Brussels, Belgium, Feb. 12, 2020. NATO Defense Ministers met in Brussels on Wednesday to begin the two-day meeting.