Washington (CNN) President Donald Trump said Friday that the southern border is "under siege" -- a day after his administration released statistics that showed illegal border crossings held steady in April and are in line with historical trends.

"Our Southern Border is under siege. Congress must act now to change our weak and ineffective immigration laws. Must build a Wall. Mexico, which has a massive crime problem, is doing little to help!" Trump wrote on Twitter Friday.

Our Southern Border is under siege. Congress must act now to change our weak and ineffective immigration laws. Must build a Wall. Mexico, which has a massive crime problem, is doing little to help! — Donald J. Trump (@realDonaldTrump) May 4, 2018

Although there was a significant spike in border crossings in March, figures released Thursday by US Customs and Border Protection show that the number of apprehensions in April roughly held steady compared to that month. Border crossings also remain in line with historic seasonal trends, and numbers are still consistent with Obama administration years -- slightly below fiscal years 2013 and 2014 but slightly above 2015 and 2016.

Trump's claim on Friday that Mexico is "doing little to help" also contrasts with some public statements by members of his administration, including Department of Homeland Security Secretary Kirstjen Nielsen, who thanked Mexican President Enrique Peña Nieto in March for "helping to foster a close partnership" with her department.