The U.S. will send an additional 5,000 troops ​to Poland, President Trump said Thursday. Why it matters: Trump's surprise announcement came a week after the Pentagon abruptly canceled a planned deployment of 4,000 troops to Poland. The Trump administration had previously said 5,000 troops would be withdrawn from Germany and that further troop reductions in Europe were expected. Driving the news: Trump wrote on Truth Social that his decision was based on the election last year of Poland's conservative President Karol Nawrocki, whom he endorsed. Background: Poland has in recent months faced threats from Russia that included NATO and Polish forces having to shoot down Russian drones that had violated the EU country's airspace. Polish officials announced this week the detention of three citizens who are suspected of spying on NATO for Moscow and preparing sabotage and disinformation operations. The Pentagon referred Axios to the White House for comment on the matter.…