Nancy Pelosi is the Speaker of the US House of Representatives. She is 2 heartbeats away from being President (she would become president if both the President and Vice President became incapacitated).

The House is similar to the UK Parliament. She is elected to her position by the members of the House.

Since Democracts control the House this term, they elected Nancy Pelosi as Speaker for this term.

The President has primary responsibility for foreign affairs. The Speaker taking this action could be interpretted as stepping on the toes of the President, or could have tacit approval of the President as a kind of stalking horse.