 THIS IS CBS NEWS ON THE HOUR. SPONSORED BY O'REILLY AUTO PARTS. I'M DEBRA RODRIGUEZ. WE BEGIN IN WASHINGTON WHERE SECRET SERVICE DIRECTOR KIMBERLY CHEATLE ISSUED A STATEMENT LAST HOUR SAYING THEY REVIEWED AND STRENGTHENED SECURITY AT THE REPUBLICAN NATIONAL CONVENTION AFTER SATURDAY'S ASSASSINATION ATTEMPT ON FORMER PRESIDENT DONALD TRUMP. HE ARRIVED IN MILWAUKEE LAST