The Associated Press on Monday fired a national security reporter who had provided erroneous information about a missile strike in Poland last week that resulted in a widely circulated but inaccurate news alert and story suggesting Russia was responsible for the incident.But the initial AP alert, sent to thousands of news outlets around the world, suggested a dire new escalation of Russia’s invasion of Ukraine.Poland is a NATO member, and a Russian attack on its territory might have invoked a western military response under the treaty organization’s mutual self-defense provisions.It said that its anonymous source was wrong and that “subsequent reporting showed that the missiles were Russian-made and most likely fired by Ukraine in defense against a Russian attack.”LaPorta’s firing was first reported Monday evening by the Daily Beast.We do not make these decisions lightly, nor are they based on isolated incidents.”Internal AP communications viewed by The Post show some confusion and misunderstanding during the preparations of the erroneous report."