US President George W. Bush said Monday that Washington can help calm the "testy situation" between Afghanistan and Pakistan, but refused to endorse Afghan President Hamid Karzai's threat to send troops across the border as a means to target terrorists. Bush called for leaders of Afghanistan and Pakistan to hold talks and share intelligence as both confront notorious Taliban leaders. "There's a lot of common ground," Bush said. "It's in no one's interest that extremists have a safe haven from which to operate. Obviously, it's a testy situation there." Bush declined to answer when asked directly whether he supports Karzai's threat to send troops in Afghanistan. Karzai said Sunday that Afghanistan has a right to send troops into Pakistan because Taliban militants cross over from Pakistan to attack Afghan and foreign forces. Bush said, though, that he understands Karzai's concerns. "We can help," Bush said. "We can help calm the situation down."