[A migrant sits in front of his tent on a windy day in the makeshift refugee camp at the northern Greek border point of Idomeni, Greece, Thursday, March 24, 2016. Conditions in Idomeni, where thousands have been stranded since the border shut to refugees earlier this month, have steadily deteriorated, exacerbated by days of rain that have turned the fields into muddy swamps. (AP Photo/Darko Vojinovic)]WARSAW, Poland (AP) — Poland's president on Thursday threw his support behind a government decision to renege on a deal to accept thousands of refugees, blaming security concerns raised by Tuesday's attacks in Brussels.