1762
u . s . officials say some intelligence indicates a red line may have been drawn around the capital with republican guard units ordered to use chemical weapons once u . s . and allied troops cross it .
 weapons: instrument; units: attacker; capital: place; troops: target
Given event type and trigger, please tell me the arguments of all the listed option. Output format is "name1: role1; name2: role2". 
Event type: attack 
  Option: victim, attacker, place, target, instrument 
Text: {0} 
Answer:
 weapons: instrument; units: attacker; capital: place; troops: target