Republican lawmakers are facing an internal battle over defense spending as prominent Republicans including Senate Minority Leader Mitch McConnell (Ky.) and Sen. Roger Wicker (Miss.), the top Republican on the Senate Armed Services Committee, are pushing for big increases while conservatives are raising alarms over the debt. The battle within the GOP over how much to increase defense spending to deter threats from Russia, China and Iran will burst into public next month when the Senate is set to debate the annual National Defense Authorization Act. McConnell and Wicker are laying the groundwork for that debate by calling for major...