show the flag

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• verb literally To display the flag of one's country, especially as an expression of patriotic pride.
• verb idiomatic Of a naval vessel or military force, to identify itself by displaying the flag of its country of origin, especially in order to establish an authoritative presence and to exert diplomatic or political influence.
• verb idiomatic, by extension To represent one's country or some other group in a manner intended to suggest the authority or importance of that country or group.